Document and Entity Information	6 Months Ended
Document and Entity Information	Jun. 30, 2013	Aug. 02, 2013
Document and Entity Information [Abstract]
Entity Registrant Name	KIRBY CORPORATION
Entity Central Index Key	0000056047
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		56,768,000
Document Fiscal Year Focus	2013
Document Fiscal Period Focus	Q2
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2013

CONDENSED BALANCE SHEETS (Unaudited) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Current assets:
Cash and cash equivalents	$ 5,263	$ 11,059
Accounts receivable:
Trade - less allowance for doubtful accounts	331,131	313,182
Other	46,489	43,074
Inventories - net	139,547	177,397
Prepaid expenses and other current assets	38,277	39,248
Deferred income taxes	6,464	12,296
Total current assets	567,171	596,256
Property and equipment	3,332,462	3,219,113
Less accumulated depreciation	(948,499)	(903,948)
Property and equipment - net	2,383,963	2,315,165
Goodwill	599,001	596,030
Other assets	174,174	145,677
Total assets	3,724,309	3,653,128
Current liabilities:
Current portion of long-term debt	78,000	65,000
Income taxes payable	4,107	2,369
Accounts payable	165,502	156,763
Accrued liabilities	121,973	114,031
Deferred revenues	31,506	16,857
Total current liabilities	401,088	355,020
Long-term debt - less current portion	943,240	1,070,110
Deferred income taxes	467,885	426,096
Other long-term liabilities	75,936	94,848
Total long-term liabilities	1,487,061	1,591,054
Contingencies and commitments
Kirby stockholders' equity:
Common stock, $.10 par value per share. Authorized 120,000,000 shares, issued 59,776,000 shares	5,978	5,978
Additional paid-in capital	401,826	397,785
Accumulated other comprehensive income - net	(58,237)	(61,127)
Retained earnings	1,558,750	1,439,079
Treasury stock - at cost, 3,021,000 at June 30, 2013 and 3,191,000 at December 31, 2012	(83,596)	(86,747)
Total Kirby stockholders' equity	1,824,721	1,694,968
Noncontrolling interests	11,439	12,086
Total equity	1,836,160	1,707,054
Total liabilities and equity	$ 3,724,309	$ 3,653,128

CONDENSED BALANCE SHEETS (Unaudited) (Parenthetical) (USD $)	Jun. 30, 2013	Dec. 31, 2012
Equity:
Common stock, par value per share (in dollars per share)	$ 0.10	$ 0.10
Common stock, shares authorized (in shares)	120,000,000	120,000,000
Common stock, shares issued (in shares)	59,776,000	59,776,000
Treasury stock, shares (in shares)	3,020,000	3,191,000

CONDENSED STATEMENTS OF EARNINGS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues:
Marine transportation	$ 423,868	$ 342,195	$ 842,386	$ 678,152
Diesel engine services	140,040	169,653	280,307	400,631
Total revenues	563,908	511,848	1,122,693	1,078,783
Costs and expenses:
Costs of sales and operating expenses	369,587	345,916	738,861	730,275
Selling, general and administrative	40,938	43,199	85,094	96,299
Taxes, other than on income	4,397	3,907	8,875	7,821
Depreciation and amortization	40,271	35,197	81,267	71,671
Loss on disposition of assets	(537)	(69)	(505)	(41)
Total costs and expenses	454,656	428,150	913,592	906,025
Operating income	109,252	83,698	209,101	172,758
Other income	101	30	176	179
Interest expense	(7,219)	(5,901)	(15,207)	(11,741)
Earnings before taxes on income	102,134	77,827	194,070	161,196
Provision for taxes on income	(38,342)	(29,392)	(72,726)	(60,882)
Net earnings	63,792	48,435	121,344	100,314
Less: Net earnings attributable to noncontrolling interests	(699)	(884)	(1,673)	(1,819)
Net earnings attributable to Kirby	$ 63,093	$ 47,551	$ 119,671	$ 98,495
Net earnings per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 1.11	$ 0.85	$ 2.11	$ 1.76
Diluted (in dollars per share)	$ 1.11	$ 0.85	$ 2.10	$ 1.76

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

CONDENSED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) [Abstract]

Net earnings

$ 63,792

$ 48,435

$ 121,344

$ 100,314

Other comprehensive income (loss), net of taxes:

Pension and postretirement benefits

494

(1,268)

1,671

(279)

Foreign currency translation adjustments

^[1]

152

^[1]

249

^[1]

447

^[1]

Change in fair value of derivative instruments

(4)

1,420

970

2,500

Total comprehensive income (loss), net of taxes

534

^[2]

304

^[2]

2,890

^[2]

2,668

^[2]

Total comprehensive income, net of taxes

64,326

48,739

124,234

102,982

Net earnings attributable to noncontrolling interests

(699)

(884)

(1,673)

(1,819)

Comprehensive income attributable to Kirby

$ 63,627

$ 47,855

$ 122,561

$ 101,163

[1]	Actuarial gains (losses) are amortized into costs of sales and operating expenses or selling, general and administrative expenses as appropriate. (See Note 12 – Retirement Plans)
[2]	Reclassifications to net earnings of derivatives qualifying as effective hedges are recognized in interest expense or costs of sales and operating expenses as appropriate. (See Note 6 – Derivative Instruments)

CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) (USD $)	6 Months Ended
CONDENSED STATEMENTS OF CASH FLOWS (Unaudited) (USD $)	Jun. 30, 2013	Jun. 30, 2012
Cash flows from operating activities:
Net earnings	$ 121,344,000	$ 100,314,000
Adjustments to reconcile net earnings to net cash provided by operations:
Depreciation and amortization	81,267,000	71,671,000
Provision for deferred income taxes	47,883,000	33,774,000
Amortization of unearned share-based compensation	5,061,000	4,489,000
Other	3,475,000	2,127,000
Decrease in cash flows resulting from changes in operating assets and liabilities, net	10,245,000	(75,773,000)
Net cash provided by operating activities	269,275,000	136,602,000
Cash flows from investing activities:
Capital expenditures	(168,175,000)	(153,846,000)
Acquisition of businesses and marine equipment	(3,643,000)	0
Proceeds from disposition of assets	13,111,000	6,651,000
Net cash used in investing activities	(158,707,000)	(147,195,000)
Cash flows from financing activities:
Payments on bank credit facilities, net	(112,870,000)	10,530,000
Borrowings on long-term debt	225,000,000	0
Payments on long-term debt	(226,000,000)	(13,003,000)
Proceeds from exercise of stock options	2,573,000	1,250,000
Payment of contingent liability	(5,000,000)	0
Excess tax benefit from equity compensation plans	2,253,000	2,375,000
Other	(2,320,000)	(1,003,000)
Net cash used in financing activities	(116,364,000)	149,000
Decrease in cash and cash equivalents	(5,796,000)	(10,444,000)
Cash and cash equivalents, beginning of year	11,059,000	16,249,000
Cash and cash equivalents, end of period	5,263,000	5,805,000
Cash paid (received) during the period:
Interest	8,012,000	10,619,000
Income taxes	$ 17,969,000	$ 19,174,000

Management Opinion	6 Months Ended
Management Opinion	Jun. 30, 2013
Management Opinion [Abstract]
Management Opinion	In the opinion of management, the accompanying unaudited condensed financial statements of Kirby Corporation and consolidated subsidiaries (the “Company”) contain all adjustments (consisting of only normal recurring accruals) necessary to present fairly the financial position as of June 30, 2013 and December 31, 2012, and the results of operations for the three months and six months ended June 30, 2013 and 2012.

BASIS FOR PREPARATION OF THE CONDENSED FINANCIAL STATEMENTS

6 Months Ended

Jun. 30, 2013

BASIS FOR PREPARATION OF THE CONDENSED FINANCIAL STATEMENTS [Abstract]

BASIS FOR PREPARATION OF THE CONDENSED FINANCIAL STATEMENTS

(1)	BASIS FOR PREPARATION OF THE CONDENSED FINANCIAL STATEMENTS

The condensed financial statements included herein have been prepared by the Company, without audit, pursuant to the rules and regulations of the Securities and Exchange Commission. Although the Company believes that the disclosures are adequate to make the information presented not misleading, certain information and footnote disclosures, including significant accounting policies normally included in annual financial statements, have been condensed or omitted pursuant to such rules and regulations. It is suggested that these condensed financial statements be read in conjunction with the Company’s Annual Report on Form 10-K for the year ended December 31, 2012.

ACCOUNTING STANDARDS ADOPTIONS

6 Months Ended

Jun. 30, 2013

ACCOUNTING STANDARDS ADOPTIONS [Abstract]

ACCOUNTING STANDARDS ADOPTIONS

(2)	ACCOUNTING STANDARDS ADOPTION

In February 2013, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2013-02, “Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income” (“ASU 2013-02”). ASU 2013-02 established the effective date for the requirement to present components of reclassifications out of accumulated other comprehensive income (“OCI”) on the face of the financial statements. The adoption of ASU 2013-02 in the first quarter of 2013 did not have an impact on the Company’s consolidated financial statements except the Company has applied these provisions to its presentation of consolidated financial statements.

ACQUISITIONS

6 Months Ended

Jun. 30, 2013

ACQUISITIONS [Abstract]

ACQUISITIONS

(3)	ACQUISITIONS

On December 28, 2012, the Company purchased the assets of Flag Service & Maintenance, Inc. (“Flag”) for $6,864,000 in cash. Flag was an East Coast high-speed diesel engine service provider, operating factory-authorized full service marine dealerships for Caterpillar, Cummins, MTU and John Deere diesel engines.

On December 14, 2012, the Company completed the acquisition of Penn Maritime Inc. and Maritime Investments LLC (“Penn”), an operator of tank barges and tugboats participating in the coastal transportation of primarily refinery feedstocks, asphalt and crude oil in the United States. The total value of the transaction was $300,538,000, consisting of $146,750,000 of cash, $29,080,000 through the issuance of 500,000 shares of Company common stock valued at $58.16 per share, and $124,708,000 of cash for the retirement of Penn’s debt. Penn’s fleet, comprised of 18 double hull tank barges with a capacity of 1.9 million barrels and 16 tugboats, operates along the East Coast and Gulf Coast of the United States.

On November 1, 2012, the Company purchased from Allied Transportation Company (“Allied”) 10 coastal tank barges with a total capacity of 680,000 barrels, three offshore dry-bulk barges with a total capacity of 48,000 deadweight tons and seven coastal tugboats for $108,547,000 in cash plus a provision for up to $10,000,000 that will be paid contingent on developments with the sugar provisions in the United States Farm Bill. The fair value of the contingent liability recorded at the acquisition date was $9,756,000. A payment of $5,000,000 was made in the 2013 first quarter on the contingent liability. Allied provided coastal transportation of petrochemicals as well as dry sugar products in the Northeast, Atlantic and Gulf Coast regions of the United States.

FAIR VALUE MEASUREMENTS

6 Months Ended

Jun. 30, 2013

FAIR VALUE MEASUREMENTS [Abstract]

FAIR VALUE MEASUREMENTS

(5)	FAIR VALUE MEASUREMENTS

The accounting guidance for using fair value to measure certain assets and liabilities establishes a three tier value hierarchy, which prioritizes the inputs to valuation techniques used in measuring fair value. These tiers include: Level 1, defined as observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2, defined as inputs other than quoted prices in active markets that are either directly or indirectly observable; and Level 3, defined as unobservable inputs in which little, if any, market data exists, therefore requiring an entity to develop its own assumptions about the assumptions that market participants would use in pricing the asset or liability.

The following table summarizes the assets and liabilities measured at fair value on a recurring basis as of June 30, 2013 and December 31, 2012 (in thousands):

June 30, 2013:	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value Measurements
Assets:
Derivatives	$	—	$	—	$	—	$	—

Liabilities:
Derivatives	$	—	$	30	$	—	$	30
Contingent liabilities		—		—		12,780		12,780
	$	—	$	30	$	12,780	$	12,810

December 31, 2012:	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value Measurements
Assets:
Derivatives	$	—	$	—	$	—	$	—

Liabilities:
Derivatives	$	—	$	1,525	$	—	$	1,525
Contingent liabilities		—		—		28,067		28,067
	$	—	$	1,525	$	28,067	$	29,592

The fair value of the Company’s derivative instruments is more fully described below in Note 6, Derivative Instruments.

In connection with the acquisition of Allied on November 1, 2012, Allied’s former owners are eligible to receive up to an additional $10,000,000 payable in 2013 through 2015, contingent on developments with the sugar provisions in the United States Farm Bill. The fair value of the contingent liability recorded at the acquisition date was $9,756,000. The fair value of the contingent liability is based on a valuation of the estimated fair value of the liability after probability weighting and discounting various potential payments. A payment of $5,000,000 was made in the 2013 first quarter on the contingent liability. The increase in the fair value of the contingent liability for the three months and six months ended June 30, 2013 was $14,000 and $113,000, respectively, was charged to selling, general and administrative expense. As of June 30, 2013, the Company had recorded a contingent liability of $4,880,000.

In connection with the acquisition of United Holdings LLC ("United") on April 15, 2011, United’s former owners are eligible to receive a three-year earnout provision for up to an additional $50,000,000 payable in 2014, dependent on achieving certain financial targets. The fair value of the contingent earnout liability recorded at the acquisition date was $16,300,000. The fair value of the earnout is based on a valuation of the estimated fair value of the liability after probability weighting and discounting various potential payments. The decrease in the fair value of the earnout liability for the three months and six months ended June 30, 2013 was $6,100,000 and $10,400,000, respectively, was credited to selling, general and administrative expense. As of June 30, 2013, the Company had recorded an earnout liability of $7,900,000.

The estimated fair value of total debt outstanding at June 30, 2013 and December 31, 2012 was $995,608,000 and $1,130,967,000, respectively, which differs from the carrying amounts of $1,021,240,000 and $1,135,110,000, respectively, included in the consolidated financial statements. The fair value was determined using an income approach that relies on inputs such as yield curves. Cash and cash equivalents, accounts receivable, accounts payable and accrued liabilities have carrying values that approximate fair value due to the short-term maturity of these financial instruments.

Certain assets are measured at fair value on a nonrecurring basis and therefore are not included in the table above. These assets are adjusted to fair value when there is evidence of impairment. During the six months ended June 30, 2013, there was no indication that the Company’s long-lived assets were impaired, and accordingly, measurement at fair value was not required.

DERIVATIVE INSTRUMENTS

6 Months Ended

Jun. 30, 2013

DERIVATIVE INSTRUMENTS [Abstract]

DERIVATIVE INSTRUMENTS

(6)	DERIVATIVE INSTRUMENTS

The Company recognizes all derivative instruments at fair value in the balance sheet as either assets or liabilities. The accounting for changes in the fair value of a derivative instrument depends on the intended use of the derivative and the resulting designation, which is established at the inception date of a derivative. For derivative instruments designated as cash flow hedges, changes in fair value, to the extent the hedge is effective, are recognized in OCI until the hedged item is recognized in earnings. Hedge effectiveness is measured at least quarterly based on the cumulative difference between the fair value of the derivative contract and the hedged item over time. Any change in fair value resulting from ineffectiveness is recognized immediately in earnings.

Interest Rate Risk Management

From time to time, the Company has utilized derivative financial instruments with respect to a portion of its interest rate risks to achieve a more predictable cash flow by reducing its exposure to interest rate fluctuations. These transactions generally are interest rate swap agreements and are entered into with large multinational banks. On February 28, 2013, all of the Company’s outstanding interest rate swaps expired. These interest rate swaps, with a total notional amount of $200,000,000, were designated as cash flow hedges.

Foreign Currency Risk Management

From time to time, the Company has utilized derivative financial instruments with respect to its forecasted foreign currency transactions to attempt to reduce the risk of its exposure to foreign currency rate fluctuations in its transactions denominated in foreign currency. These transactions, which relate to foreign currency obligations for the purchase of equipment from foreign suppliers or foreign currency receipts from foreign customers, generally are forward contracts or purchased call options and are entered into with large multinational banks.

As of June 30, 2013, the Company had a forward contract with a notional amount of $469,000 to hedge its exposure to foreign currency rate fluctuations in expected foreign currency transactions. This contract expires in the first quarter of 2014. This forward contract is designated as a cash flow hedge, therefore, the change in fair value, to the extent the forward contract is effective, is recognized in OCI until the forward contract expires and is recognized in cost of sales and operating expenses.

Fair Value of Derivative Instruments

The following table sets forth the fair value of the Company’s derivative instruments recorded as liabilities located on the consolidated balance sheet at June 30, 2013 and December 31, 2012 (in thousands):

Liability Derivatives	Balance Sheet Location	June 30, 2013		December 31, 2012
Derivatives designated as hedging instruments under ASC 815:

Foreign currency contracts	Other accrued liabilities	$	30	$	−
Foreign currency contracts	Other long-term liabilities		−		39
Interest rate contracts	Other accrued liabilities		−		1,486

Total derivatives designated as hedging instruments under ASC 815		$	30	$	1,525
Total liability derivatives		$	30	$	1,525

Fair value amounts were derived as of June 30, 2013 and December 31, 2012 utilizing fair value models of the Company and its counterparties on the Company’s portfolio of derivative instruments. These fair value models use the income approach that relies on inputs such as yield curves, currency exchange rates and forward prices. The fair value of the Company’s derivative instruments is described above in Note 5, Fair Value Measurements.

Cash Flow Hedges

For derivative instruments that are designated and qualify as cash flow hedges, the effective portion of the gain or loss on the derivative is reported as a component of OCI and reclassified into earnings in the same period or periods during which the hedged transaction affects earnings. Gains and losses on the derivative representing either hedge ineffectiveness or hedge components excluded from the assessment of effectiveness are recognized in current earnings. Any ineffectiveness related to the Company’s hedges was not material for any of the periods presented.

The following table sets forth the location and amount of gains and losses on the Company’s derivative instruments in the consolidated statements of earnings for the three months and six months ended June 30, 2013 and 2012 (in thousands):

	Location of Gain (Loss)		Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)					Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Reclassified from		Three months ended					Three months ended
Derivatives in ASC 815 Cash	Accumulated OCI into Income		June 30,					June 30,
Flow Hedging Relationships:	(Effective Portion)		2013			2012		2013		2012
Interest rate contracts	Interest expense	$	─		$	2,030	$	─	$	(2,056	)

Foreign exchange contracts	Cost and sales of operating expenses		(8	)		172	─			─	)

Total		$	(8	)	$	2,202	$	─	$	(2,056	)

	Location of Gain (Loss)		Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)				Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Reclassified from		Six months ended				Six months ended
Derivatives in ASC 815 Cash	Accumulated OCI into Income		June 30,				June 30,
Flow Hedging Relationships:	(Effective Portion)		2013		2012		2013			2012
Interest rate contracts	Interest expense	$	1,486	$	3,623	$	(1,389	)	$	(4,100	)

Foreign exchange contracts	Cost and sales of operating expenses		7		249	─				(2	)

Total		$	1,493	$	3,872	$	(1,389	)	$	(4,102	)

The Company expects $30,000 of net losses on foreign currency contracts included in accumulated OCI will be transferred into earnings over the next year based on current spot rates.

STOCK AWARD PLANS

6 Months Ended

Jun. 30, 2013

STOCK AWARD PLANS [Abstract]

STOCK AWARD PLANS

(7)	STOCK AWARD PLANS

The Company has share-based compensation plans which are described below. The compensation cost that has been charged against earnings for the Company’s stock award plans and the income tax benefit recognized in the statement of earnings for stock awards for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Compensation cost		$	2,927		$	2,583		$	5,061		$	4,489
Income tax benefit		$	1,106		$	987		$	1,913		$	1,715

The Company has an employee stock award plan for selected officers and other key employees which provide for the issuance of stock options, restricted stock and performance awards. The exercise price for each option equals the fair market value per share of the Company’s common stock on the date of grant. The terms of the options granted prior to January 25, 2010 are five years and vest ratably over three years. Options granted on or after January 25, 2010 have terms of seven years and vest ratably over three years. No performance awards payable in stock have been awarded under the Plan. At June 30, 2013, 2,678,355 shares were available for future grants under the employee plan and no outstanding stock options under the employee plan were issued with stock appreciation rights.

The following is a summary of the stock option activity under the employee plan described above for the six months ended June 30, 2013:

	Outstanding Non- Qualified or Nonincentive Stock Awards			Weighted Average Exercise Price
Outstanding at December 31, 2012		351,173		$	45.54
Granted		109,560		$	70.65
Exercised		(43,449	)	$	28.75
Outstanding at June 30, 2013		417,284		$	53.88

The following table summarizes information about the Company’s outstanding and exercisable stock options under the employee plan at June 30, 2013:

		Options Outstanding								Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life in Years		Weighted Average Exercise Price		Aggregate Intrinsic Value		Number Exercisable		Weighted Average Exercise Price		Aggregate Intrinsic Value
$	23.98 - 32.56		93,249		3.4	$	31.96				93,249	$	31.96
$	34.40 - 36.35		14,000		1.3	$	34.96				14,000	$	34.96
$	46.74		100,569		4.6	$	46.74				67,039	$	46.74
$	65.28 - 70.65		209,466		6.1	$	68.34				33,299	$	65.80
$	23.98 - 70.65		417,284		5.0	$	53.88	$	10,706,000		207,587	$	42.36	$	7,717,000

The following is a summary of the restricted stock award activity under the employee plan described above for the six months ended June 30, 2013:

	Unvested Restricted Stock Award Shares			Weighted Average Grant Date Fair Value Per Share
Nonvested balance at December 31, 2012		418,128		$	45.39
Granted		128,125		$	68.28
Vested		(138,794	)	$	40.69
Forfeited		(6,582	)	$	63.91
Nonvested balance at June 30, 2013		400,877		$	54.03

The Company has a director stock award plan for nonemployee directors of the Company which provides for the issuance of stock options and restricted stock. The director plan provides for the automatic grants of stock options and restricted stock to nonemployee directors on the date of first election as a director and after each annual meeting of stockholders. In addition, the director plan allows for the issuance of stock options or restricted stock in lieu of cash for all or part of the annual director fee at the option of the director. The exercise prices for all options granted under the plan are equal to the fair market value per share of the Company’s common stock on the date of grant. The terms of the options are ten years. The options granted to a director when first elected vest immediately. The options granted and restricted stock issued after each annual meeting of stockholders vest six months after the date of grant. Options granted and restricted stock issued in lieu of cash director fees vest in equal quarterly increments during the year to which they relate. At June 30, 2013, 610,041 shares were available for future grants under the director plan. The director stock award plan is intended as an incentive to attract and retain qualified independent directors.

The following is a summary of the stock option activity under the director plan described above for the six months ended June 30, 2013:

	Outstanding Non- Qualified or Nonincentive Stock Options			Weighted Average Exercise Price
Outstanding at December 31, 2012		345,938		$	45.84
Granted		54,958		$	75.17
Exercised		(36,000	)	$	36.79
Outstanding at June 30, 2013		364,896		$	51.15

The following table summarizes information about the Company’s outstanding and exercisable stock options under the director plan at June 30, 2013:

		Options Outstanding								Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life in Years		Weighted Average Exercise Price		Aggregate Intrinsic Value		Number Exercisable		Weighted Average Exercise Price		Aggregate Intrinsic Value
$	17.88		12,000		0.8	$	17.88				12,000	$	17.88
$	20.28- 29.60		36,000		4.5	$	26.49				36,000	$	26.49
$	35.17- 36.82		56,036		3.3	$	35.91				56,036	$	35.91
$	41.24- 56.45		145,596		6.5	$	52.14				145,596	$	52.14
$	61.89- 62.48		60,306		8.9	$	62.38				60,306	$	62.38
$	75.17		54,958		9.8	$	75.17				239	$	75.17
$	17.88- 75.17		364,896		6.5	$	51.15	$	10,358,000		310,177	$	46.92	$	10,119,000

The following is a summary of the restricted stock award activity under the director plan described above for the six months ended June 30, 2013:

	Unvested Restricted Stock Award Shares			Weighted Average Grant Date Fair Value Per Share
Nonvested balance at December 31, 2012		348		$	62.99
Granted		10,536		$	75.65
Vested		(732	)	$	69.63
Nonvested balance at June 30, 2013		10,152		$	75.65

The total intrinsic value of all stock options exercised under all of the Company’s plans was $3,342,000 and $1,612,000 for the six months ended June 30, 2013 and 2012, respectively. The actual tax benefit realized for tax deductions from stock option exercises was $1,263,000 and $616,000 for the six months ended June 30, 2013 and 2012, respectively.

The total intrinsic value of all the restricted stock vestings under all of the Company’s plans was $9,230,000 and $11,004,000 for the six months ended June 30, 2013 and 2012, respectively. The actual tax benefit realized for tax deductions from restricted stock vestings was $3,489,000 and $4,204,000 for the six months ended June 30, 2013 and 2012, respectively.

As of June 30, 2013, there was $4,720,000 of unrecognized compensation cost related to nonvested stock options and $19,325,000 related to restricted stock. The stock options are expected to be recognized over a weighted average period of approximately 1.5 years and restricted stock over approximately 3.1 years. The total fair value of options vested was $1,714,000 and $1,326,000 during the six months ended June 30, 2013 and 2012, respectively. The fair value of the restricted stock vested was $9,230,000 and $11,004,000 for the six months ended June 30, 2013 and 2012, respectively.

The weighted average per share fair value of stock options granted during the six months ended June 30, 2013 and 2012 was $25.07 and $22.15, respectively. The fair value of the stock options granted during the six months ended June 30, 2013 and 2012 was $4,125,000 and $3,461,000, respectively. The Company currently uses treasury stock shares for restricted stock grants and stock option exercises. The fair value of each stock option was determined using the Black-Scholes option pricing model. The key input variables used in valuing the options during the six months ended June 30, 2013 and 2012 were as follows:

	Six months ended June 30,
	2013		2012
Dividend yield	None		None
Average risk-free interest rate		1.1%		1.1%
Stock price volatility		34%		33%
Estimated option term	Six years or seven years		Six years or seven years

OTHER COMPREHENSIVE INCOME

6 Months Ended

Jun. 30, 2013

OTHER COMPREHENSIVE INCOME [Abstract]

OTHER COMPREHENSIVE INCOME

(8)	OTHER COMPREHENSIVE INCOME

The Company’s changes in other comprehensive income for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

	Three months ended June 30,
	2013									2012
	Gross Amount			Income Tax (Provision) Benefit			Net Amount			Gross Amount			Income Tax (Provision) Benefit			Net Amount

Pension and postretirement benefits (a):
Amortization of net actuarial loss	$	1,934		$	(740	)	$	1,194		$	1,794		$	(704	)	$	1,090
Actuarial gains (losses)		(1,134	)		434			(700	)		(3,851	)		1,493			(2,358	)

Foreign currency translation adjustments		44			—			44			152			—			152

Change in fair value of derivative instruments (b):
Unrealized gains (losses)		(7	)		3			(4	)		4,258			(1,520	)		2,738
Reclassified to net earnings		−			−			−			(2,056	)		738			(1,318	)
Total	$	837		$	(303	)	$	534		$	297		$	7		$	304

	Six months ended June 30,
	2013									2012
	Gross Amount			Income Tax (Provision) Benefit			Net Amount			Gross Amount			Income Tax (Provision) Benefit			Net Amount

Pension and postretirement benefits (a):
Amortization of net actuarial loss	$	3,840		$	(1,469	)	$	2,371		$	3,395		$	(1,316	)	$	2,079
Actuarial gains (losses)		(1,134	)		434			(700	)		(3,851	)		1,493			(2,358	)

Foreign currency translation adjustments		249			—			249			447			—			447

Change in fair value of derivative instruments (b):
Unrealized gains (losses)		2,882			(1,009	)		1,873			7,974			(2,826	)		5,148
Reclassified to net earnings		(1,389	)		486			(903	)		(4,102	)		1,454			(2,648	)
Total	$	4,448		$	(1,558	)	$	2,890		$	3,863		$	(1,195	)	$	2,668

(a)	Actuarial gains (losses) are amortized into costs of sales and operating expenses or selling, general and administrative expenses as appropriate. (See Note 12 – Retirement Plans)

(b)	Reclassifications to net earnings of derivatives qualifying as effective hedges are recognized in interest expense or costs of sales and operating expenses as appropriate. (See Note 6 – Derivative Instruments)

SEGMENT DATA

6 Months Ended

Jun. 30, 2013

SEGMENT DATA [Abstract]

SEGMENT DATA

(9)	SEGMENT DATA

The Company’s operations are classified into two reportable business segments as follows:

Marine Transportation — Marine transportation principally by United States flag vessels of liquid cargoes throughout the United States inland waterway system, coastwise along all three United States coasts and in Alaska and Hawaii and, to a lesser extent, United States coastal transportation of dry-bulk cargoes. The principal products transported include petrochemicals, black oil, refined petroleum products and agricultural chemicals.

Diesel Engine Services — Provides after-market services for medium-speed and high-speed diesel engines, reduction gears and ancillary products for marine and power generation applications, distributes and services high-speed diesel engines, transmissions, pumps and compression products, and manufactures and remanufactures oilfield service equipment, including pressure pumping units, for the land-based pressure pumping and oilfield service markets.

The Company’s two reportable business segments are managed separately based on fundamental differences in their operations. The Company evaluates the performance of its segments based on the contributions to operating income of the respective segments, before income taxes, interest, gains or losses on disposition of assets, other nonoperating income, noncontrolling interests, accounting changes, and nonrecurring items. Intersegment sales for the three months and six months ended June 30, 2013 and 2012 were not significant.

The following table sets forth the Company’s revenues and profit or loss by reportable segment for the three months and six months ended June 30, 2013 and 2012 and total assets as of June 30, 2013 and December 31, 2012 (in thousands):

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Revenues:
Marine transportation	$	423,868		$	342,195		$	842,386		$	678,152
Diesel engine services		140,040			169,653			280,307			400,631
	$	563,908		$	511,848		$	1,122,693		$	1,078,783
Segment profit (loss):
Marine transportation	$	97,563		$	71,730		$	186,816		$	140,220
Diesel engine services		14,932			15,118			28,954			38,672
Other		(10,361	)		(9,021	)		(21,700	)		(17,696	)
	$	102,134		$	77,827		$	194,070		$	161,196

	June 30, 2013		December 31, 2012
Total assets:
Marine transportation	$	3,054,231	$	2,951,723
Diesel engine services		616,496		647,986
Other		53,582		53,419
	$	3,724,309	$	3,653,128

The following table presents the details of “Other” segment loss for the three months and six months ended June 30, 2013 and 2012 (in thousands):

		Three months ended June 30,						Six months ended June 30,
		2013			2012			2013			2012

General corporate expenses	$	(3,780	)	$	(3,219	)	$	(7,174	)	$	(6,175	)
Gain on disposition of assets		537			69			505			41
Interest expense		(7,219	)		(5,901	)		(15,207	)		(11,741	)
Other income		101			30			176			179
	$	(10,361	)	$	(9,021	)	$	(21,700	)	$	(17,696	)

The following table presents the details of “Other” total assets as of June 30, 2013 and December 31, 2012 (in thousands):

	June 30, 2013		December 31, 2012
General corporate assets	$	51,574	$	51,611
Investment in affiliates		2,008		1,808
	$	53,582	$	53,419

TAXES ON INCOME

6 Months Ended

Jun. 30, 2013

TAXES ON INCOME [Abstract]

TAXES ON INCOME

(10)	TAXES ON INCOME

Earnings before taxes on income and details of the provision for taxes on income for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012

Earnings before taxes on income – United States	$	102,134	$	77,827	$	194,070	$	161,196
Provision for taxes on income:
Federal:
Current	$	8,102	$	10,416	$	17,532	$	20,096
Deferred		26,386		15,591		47,883		33,774
State and local		3,854		3,385		7,311		7,012
	$	38,342	$	29,392	$	72,726	$	60,882

EARNINGS PER SHARE

6 Months Ended

Jun. 30, 2013

EARNINGS PER SHARE [Abstract]

EARNINGS PER SHARE

(11)	EARNINGS PER SHARE

The following table presents the components of basic and diluted earnings per share of common stock for the three months and six months ended June 30, 2013 and 2012 (in thousands, except per share amounts):

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012

Net earnings attributable to Kirby	$	63,093		$	47,551		$	119,671		$	98,495
Undistributed earnings allocated to restricted shares		(459	)		(375	)		(859	)		(769	)
Income available to Kirby common stockholders - basic		62,634			47,176			118,812			97,726
Undistributed earnings allocated to restricted shares		459			375			859			769
Undistributed earnings reallocated to restricted shares		(457	)		(374	)		(856	)		(765	)
Income available to Kirby common stockholders - diluted	$	62,636		$	47,177		$	118,815		$	97,730

Shares outstanding:
Weighted average common stock issued and outstanding		56,752			55,869			56,712			55,839
Weighted average unvested restricted stock		(413	)		(441	)		(407	)		(436	)
Weighted average common stock outstanding - basic		56,339			55,428			56,305			55,403
Dilutive effect of stock options		190			212			188			235
Weighted average common stock outstanding - diluted		56,529			55,640			56,493			55,638

Net earnings per share attributable to Kirby common stockholders:
Basic	$	1.11		$	.85		$	2.11		$	1.76
Diluted	$	1.11		$	.85		$	2.10		$	1.76

Certain outstanding options to purchase approximately 165,000 and 157,000 shares of common stock were excluded in the computation of diluted earnings per share as of June 30, 2013 and 2012, respectively, as such stock options would have been antidilutive.

RETIREMENT PLANS

6 Months Ended

Jun. 30, 2013

RETIREMENT PLANS [Abstract]

RETIREMENT PLANS

(12)	RETIREMENT PLANS

The Company sponsors a defined benefit plan for its inland vessel personnel and shore based tankermen. The plan benefits are based on an employee’s years of service and compensation. The plan assets consist primarily of equity and fixed income securities.

The Company’s pension plan funding strategy has historically been to contribute an amount equal to the greater of the minimum required contribution under ERISA or the amount necessary to fully fund the plan on an accumulated benefit obligation (“ABO”) basis at the end of the fiscal year. The ABO is based on a variety of demographic and economic assumptions, and the pension plan assets’ returns are subject to various risks, including market and interest rate risk, making an accurate prediction of the pension plan contribution difficult. Based on current pension plan assets and market conditions, the Company does not expect to make a contribution to its pension plan prior to December 31, 2013 to fund its 2013 pension plan obligations. As of June 30, 2013, no 2013 year contributions have been made.

The Company sponsors an unfunded defined benefit health care plan that provides limited postretirement medical benefits to employees who meet minimum age and service requirements, and to eligible dependents. The plan limits cost increases in the Company’s contribution to 4% per year. The plan is contributory, with retiree contributions adjusted annually. The plan eliminated coverage for future retirees as of December 31, 2011. The Company also has an unfunded defined benefit supplemental executive retirement plan (“SERP”) that was assumed in an acquisition in 1999. That plan ceased to accrue additional benefits effective January 1, 2000.

The components of net periodic benefit cost for the Company’s defined benefit plans for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

		Pension Benefits
		Pension Plan						SERP
		Three months ended June 30,						Three months ended June 30,
		2013			2012			2013		2012
Components of net periodic benefit cost:
Service cost	$	3,243		$	2,539		$	—	$	—
Interest cost		2,867			2,670			18		19
Expected return on plan assets		(4,039	)		(3,218	)		—		—
Amortization of actuarial loss		2,083			1,946			4		3
Net periodic benefit cost	$	4,154		$	3,937		$	22	$	22

		Pension Benefits
		Pension Plan						SERP
		Six months ended June 30,						Six months ended June 30,
		2013			2012			2013		2012
Components of net periodic benefit cost:
Service cost	$	6,414		$	5,105		$	—	$	—
Interest cost		5,702			5,254			35		37
Expected return on plan assets		(8,066	)		(6,438	)		—		—
Amortization of actuarial loss		4,139			3,698			9		7
Net periodic benefit cost	$	8,189		$	7,619		$	44	$	44

The components of net periodic benefit cost for the Company’s postretirement benefit plan for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

		Other Postretirement Benefits						Other Postretirement Benefits
		Postretirement Welfare Plan						Postretirement Welfare Plan
		Three months ended June 30,						Six months ended June 30,
		2013			2012			2013			2012
Components of net periodic benefit cost:
Service cost	$	—		$	—		$	—		$	—
Interest cost		28			34			56			67
Amortization of actuarial gain		(153	)		(156	)		(308	)		(310	)
Net periodic benefit cost	$	(125	)	$	(122	)	$	(252	)	$	(243	)

CONTINGENCIES

6 Months Ended

Jun. 30, 2013

CONTINGENCIES [Abstract]

CONTINGENCIES

(13)	CONTINGENCIES

On January 30, 2012 in the U.S. District Court for the District of New Jersey in a case styled Rescue Mission of El Paso., Inc., et al. v. John J. Nicola, et al., the Company, its subsidiary, K-Sea Transportation Partners L.P. ("K-Sea"), and current and former officers and directors of K-Sea were named defendants in a putative class action complaint asserting that during the period of January 30, 2009 to January 27, 2010, K-Sea allegedly failed to disclose certain facts regarding K-Sea’s operations and financial condition, and asserting violations of Sections 10(b)(5) and 20(a) of the Securities and Exchange Act of 1934 and Rule 10b-5 thereunder. Plaintiff sought class certification, compensatory damages, attorneys’ fees and costs. The Plaintiff filed its Amended Consolidated Complaint on behalf of the class on July 9, 2012. The Company filed a motion to dismiss in response to the Complaint. On June 18, 2013, the Court granted the Company's motion to dismiss the case.

The Company is involved in various legal and other proceedings which are incidental to the conduct of its business, none of which in the opinion of management will have a material effect on the Company’s financial condition, results of operations or cash flows. Management believes that it has recorded adequate reserves and believes that it has adequate insurance coverage or has meritorious defenses for these other claims and contingencies.

The Company has issued guaranties or obtained standby letters of credit and performance bonds supporting performance by the Company and its subsidiaries of contractual or contingent legal obligations of the Company and its subsidiaries incurred in the ordinary course of business. The aggregate notional value of these instruments was $45,818,000 at June 30, 2013, including $6,128,000 in letters of credit and $39,690,000 in performance bonds. All of these instruments have an expiration date within five years. The Company does not believe demand for payment under these instruments is likely and expects no material cash outlays to occur in connection with these instruments.

ACCOUNTING STANDARDS ADOPTIONS (Policies)	6 Months Ended
ACCOUNTING STANDARDS ADOPTIONS (Policies)	Jun. 30, 2013
ACCOUNTING STANDARDS ADOPTIONS [Abstract]
New Accounting Pronouncements, Policy	In February 2013, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2013-02, “Comprehensive Income (Topic 220): Reporting of Amounts Reclassified Out of Accumulated Other Comprehensive Income” (“ASU 2013-02”). ASU 2013-02 established the effective date for the requirement to present components of reclassifications out of accumulated other comprehensive income (“OCI”) on the face of the financial statements. The adoption of ASU 2013-02 in the first quarter of 2013 did not have an impact on the Company’s consolidated financial statements except the Company has applied these provisions to its presentation of consolidated financial statements.

FAIR VALUE MEASUREMENTS (Tables)

6 Months Ended

Jun. 30, 2013

FAIR VALUE MEASUREMENTS [Abstract]

Schedule of summarized assets and liabilities measured at fair value on recurring basis

The following table summarizes the assets and liabilities measured at fair value on a recurring basis as of June 30, 2013 and December 31, 2012 (in thousands):

June 30, 2013:	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value Measurements
Assets:
Derivatives	$	—	$	—	$	—	$	—

Liabilities:
Derivatives	$	—	$	30	$	—	$	30
Contingent liabilities		—		—		12,780		12,780
	$	—	$	30	$	12,780	$	12,810

December 31, 2012:	Quoted Prices in Active Markets for Identical Assets (Level 1)		Significant Other Observable Inputs (Level 2)		Significant Unobservable Inputs (Level 3)		Total Fair Value Measurements
Assets:
Derivatives	$	—	$	—	$	—	$	—

Liabilities:
Derivatives	$	—	$	1,525	$	—	$	1,525
Contingent liabilities		—		—		28,067		28,067
	$	—	$	1,525	$	28,067	$	29,592

DERIVATIVE INSTRUMENTS (Tables)

6 Months Ended

Jun. 30, 2013

DERIVATIVE INSTRUMENTS [Abstract]

Fair Value of Derivative Instruments Liabilities

Liability Derivatives	Balance Sheet Location	June 30, 2013		December 31, 2012
Derivatives designated as hedging instruments under ASC 815:

Foreign currency contracts	Other accrued liabilities	$	30	$	−
Foreign currency contracts	Other long-term liabilities		−		39
Interest rate contracts	Other accrued liabilities		−		1,486

Total derivatives designated as hedging instruments under ASC 815		$	30	$	1,525
Total liability derivatives		$	30	$	1,525

Cash Flow Hedges

	Location of Gain (Loss)		Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)					Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Reclassified from		Three months ended					Three months ended
Derivatives in ASC 815 Cash	Accumulated OCI into Income		June 30,					June 30,
Flow Hedging Relationships:	(Effective Portion)		2013			2012		2013		2012
Interest rate contracts	Interest expense	$	─		$	2,030	$	─	$	(2,056	)

Foreign exchange contracts	Cost and sales of operating expenses		(8	)		172	─			─	)

Total		$	(8	)	$	2,202	$	─	$	(2,056	)

	Location of Gain (Loss)		Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)				Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)
	Reclassified from		Six months ended				Six months ended
Derivatives in ASC 815 Cash	Accumulated OCI into Income		June 30,				June 30,
Flow Hedging Relationships:	(Effective Portion)		2013		2012		2013			2012
Interest rate contracts	Interest expense	$	1,486	$	3,623	$	(1,389	)	$	(4,100	)

Foreign exchange contracts	Cost and sales of operating expenses		7		249	─				(2	)

Total		$	1,493	$	3,872	$	(1,389	)	$	(4,102	)

STOCK AWARD PLANS (Tables)

6 Months Ended

Jun. 30, 2013

STOCK AWARD PLANS [Abstract]

Compensation cost breakdown in statement of earnings

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Compensation cost		$	2,927		$	2,583		$	5,061		$	4,489
Income tax benefit		$	1,106		$	987		$	1,913		$	1,715

Summary of stock option activity

The following is a summary of the stock option activity under the employee plan described above for the six months ended June 30, 2013:

	Outstanding Non- Qualified or Nonincentive Stock Awards			Weighted Average Exercise Price
Outstanding at December 31, 2012		351,173		$	45.54
Granted		109,560		$	70.65
Exercised		(43,449	)	$	28.75
Outstanding at June 30, 2013		417,284		$	53.88

The following table summarizes information about the Company’s outstanding and exercisable stock options under the employee plan at June 30, 2013:

		Options Outstanding								Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life in Years		Weighted Average Exercise Price		Aggregate Intrinsic Value		Number Exercisable		Weighted Average Exercise Price		Aggregate Intrinsic Value
$	23.98 - 32.56		93,249		3.4	$	31.96				93,249	$	31.96
$	34.40 - 36.35		14,000		1.3	$	34.96				14,000	$	34.96
$	46.74		100,569		4.6	$	46.74				67,039	$	46.74
$	65.28 - 70.65		209,466		6.1	$	68.34				33,299	$	65.80
$	23.98 - 70.65		417,284		5.0	$	53.88	$	10,706,000		207,587	$	42.36	$	7,717,000

The following is a summary of the stock option activity under the director plan described above for the six months ended June 30, 2013:

	Outstanding Non- Qualified or Nonincentive Stock Options			Weighted Average Exercise Price
Outstanding at December 31, 2012		345,938		$	45.84
Granted		54,958		$	75.17
Exercised		(36,000	)	$	36.79
Outstanding at June 30, 2013		364,896		$	51.15

The following table summarizes information about the Company’s outstanding and exercisable stock options under the director plan at June 30, 2013:

		Options Outstanding								Options Exercisable
Range of Exercise Prices		Number Outstanding		Weighted Average Remaining Contractual Life in Years		Weighted Average Exercise Price		Aggregate Intrinsic Value		Number Exercisable		Weighted Average Exercise Price		Aggregate Intrinsic Value
$	17.88		12,000		0.8	$	17.88				12,000	$	17.88
$	20.28- 29.60		36,000		4.5	$	26.49				36,000	$	26.49
$	35.17- 36.82		56,036		3.3	$	35.91				56,036	$	35.91
$	41.24- 56.45		145,596		6.5	$	52.14				145,596	$	52.14
$	61.89- 62.48		60,306		8.9	$	62.38				60,306	$	62.38
$	75.17		54,958		9.8	$	75.17				239	$	75.17
$	17.88- 75.17		364,896		6.5	$	51.15	$	10,358,000		310,177	$	46.92	$	10,119,000

Summary of restricted stock award activity

The following is a summary of the restricted stock award activity under the employee plan described above for the six months ended June 30, 2013:

	Unvested Restricted Stock Award Shares			Weighted Average Grant Date Fair Value Per Share
Nonvested balance at December 31, 2012		418,128		$	45.39
Granted		128,125		$	68.28
Vested		(138,794	)	$	40.69
Forfeited		(6,582	)	$	63.91
Nonvested balance at June 30, 2013		400,877		$	54.03

The following is a summary of the restricted stock award activity under the director plan described above for the six months ended June 30, 2013:

	Unvested Restricted Stock Award Shares			Weighted Average Grant Date Fair Value Per Share
Nonvested balance at December 31, 2012		348		$	62.99
Granted		10,536		$	75.65
Vested		(732	)	$	69.63
Nonvested balance at June 30, 2013		10,152		$	75.65

Summary of Stock option valuation assumptions

The fair value of each stock option was determined using the Black-Scholes option pricing model. The key input variables used in valuing the options during the six months ended June 30, 2013 and 2012 were as follows:

	Six months ended June 30,
	2013		2012
Dividend yield	None		None
Average risk-free interest rate		1.1%		1.1%
Stock price volatility		34%		33%
Estimated option term	Six years or seven years		Six years or seven years

OTHER COMPREHENSIVE INCOME (Tables)

6 Months Ended

Jun. 30, 2013

OTHER COMPREHENSIVE INCOME [Abstract]

Schedule of changes in other comprehensive income

The Company’s changes in other comprehensive income for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

	Three months ended June 30,
	2013									2012
	Gross Amount			Income Tax (Provision) Benefit			Net Amount			Gross Amount			Income Tax (Provision) Benefit			Net Amount

Pension and postretirement benefits (a):
Amortization of net actuarial loss	$	1,934		$	(740	)	$	1,194		$	1,794		$	(704	)	$	1,090
Actuarial gains (losses)		(1,134	)		434			(700	)		(3,851	)		1,493			(2,358	)

Foreign currency translation adjustments		44			—			44			152			—			152

Change in fair value of derivative instruments (b):
Unrealized gains (losses)		(7	)		3			(4	)		4,258			(1,520	)		2,738
Reclassified to net earnings		−			−			−			(2,056	)		738			(1,318	)
Total	$	837		$	(303	)	$	534		$	297		$	7		$	304

	Six months ended June 30,
	2013									2012
	Gross Amount			Income Tax (Provision) Benefit			Net Amount			Gross Amount			Income Tax (Provision) Benefit			Net Amount

Pension and postretirement benefits (a):
Amortization of net actuarial loss	$	3,840		$	(1,469	)	$	2,371		$	3,395		$	(1,316	)	$	2,079
Actuarial gains (losses)		(1,134	)		434			(700	)		(3,851	)		1,493			(2,358	)

Foreign currency translation adjustments		249			—			249			447			—			447

Change in fair value of derivative instruments (b):
Unrealized gains (losses)		2,882			(1,009	)		1,873			7,974			(2,826	)		5,148
Reclassified to net earnings		(1,389	)		486			(903	)		(4,102	)		1,454			(2,648	)
Total	$	4,448		$	(1,558	)	$	2,890		$	3,863		$	(1,195	)	$	2,668

(a)	Actuarial gains (losses) are amortized into costs of sales and operating expenses or selling, general and administrative expenses as appropriate. (See Note 12 – Retirement Plans)

(b)	Reclassifications to net earnings of derivatives qualifying as effective hedges are recognized in interest expense or costs of sales and operating expenses as appropriate. (See Note 6 – Derivative Instruments)

SEGMENT DATA (Tables)

6 Months Ended

Jun. 30, 2013

SEGMENT DATA [Abstract]

Schedule of segment reporting information, by segment

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012
Revenues:
Marine transportation	$	423,868		$	342,195		$	842,386		$	678,152
Diesel engine services		140,040			169,653			280,307			400,631
	$	563,908		$	511,848		$	1,122,693		$	1,078,783
Segment profit (loss):
Marine transportation	$	97,563		$	71,730		$	186,816		$	140,220
Diesel engine services		14,932			15,118			28,954			38,672
Other		(10,361	)		(9,021	)		(21,700	)		(17,696	)
	$	102,134		$	77,827		$	194,070		$	161,196

	June 30, 2013		December 31, 2012
Total assets:
Marine transportation	$	3,054,231	$	2,951,723
Diesel engine services		616,496		647,986
Other		53,582		53,419
	$	3,724,309	$	3,653,128

Schedule of other segment reporting information

The following table presents the details of “Other” segment loss for the three months and six months ended June 30, 2013 and 2012 (in thousands):

		Three months ended June 30,						Six months ended June 30,
		2013			2012			2013			2012

General corporate expenses	$	(3,780	)	$	(3,219	)	$	(7,174	)	$	(6,175	)
Gain on disposition of assets		537			69			505			41
Interest expense		(7,219	)		(5,901	)		(15,207	)		(11,741	)
Other income		101			30			176			179
	$	(10,361	)	$	(9,021	)	$	(21,700	)	$	(17,696	)

The following table presents the details of “Other” total assets as of June 30, 2013 and December 31, 2012 (in thousands):

	June 30, 2013		December 31, 2012
General corporate assets	$	51,574	$	51,611
Investment in affiliates		2,008		1,808
	$	53,582	$	53,419

TAXES ON INCOME (Tables)

6 Months Ended

Jun. 30, 2013

TAXES ON INCOME [Abstract]

Earnings before taxes

Earnings before taxes on income and details of the provision for taxes on income for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

	Three months ended June 30,				Six months ended June 30,
	2013		2012		2013		2012

Earnings before taxes on income – United States	$	102,134	$	77,827	$	194,070	$	161,196
Provision for taxes on income:
Federal:
Current	$	8,102	$	10,416	$	17,532	$	20,096
Deferred		26,386		15,591		47,883		33,774
State and local		3,854		3,385		7,311		7,012
	$	38,342	$	29,392	$	72,726	$	60,882

EARNINGS PER SHARE (Tables)

6 Months Ended

Jun. 30, 2013

EARNINGS PER SHARE [Abstract]

Components of basic and diluted earnings per share

	Three months ended June 30,						Six months ended June 30,
	2013			2012			2013			2012

Net earnings attributable to Kirby	$	63,093		$	47,551		$	119,671		$	98,495
Undistributed earnings allocated to restricted shares		(459	)		(375	)		(859	)		(769	)
Income available to Kirby common stockholders - basic		62,634			47,176			118,812			97,726
Undistributed earnings allocated to restricted shares		459			375			859			769
Undistributed earnings reallocated to restricted shares		(457	)		(374	)		(856	)		(765	)
Income available to Kirby common stockholders - diluted	$	62,636		$	47,177		$	118,815		$	97,730

Shares outstanding:
Weighted average common stock issued and outstanding		56,752			55,869			56,712			55,839
Weighted average unvested restricted stock		(413	)		(441	)		(407	)		(436	)
Weighted average common stock outstanding - basic		56,339			55,428			56,305			55,403
Dilutive effect of stock options		190			212			188			235
Weighted average common stock outstanding - diluted		56,529			55,640			56,493			55,638

Net earnings per share attributable to Kirby common stockholders:
Basic	$	1.11		$	.85		$	2.11		$	1.76
Diluted	$	1.11		$	.85		$	2.10		$	1.76

RETIREMENT PLANS (Tables)

6 Months Ended

Jun. 30, 2013

Pension Benefits [Member]

Defined Benefit Plan Disclosure [Line Items]

Components Of Net Periodic Benefit Cost

The components of net periodic benefit cost for the Company’s defined benefit plans for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

		Pension Benefits
		Pension Plan						SERP
		Three months ended June 30,						Three months ended June 30,
		2013			2012			2013		2012
Components of net periodic benefit cost:
Service cost	$	3,243		$	2,539		$	—	$	—
Interest cost		2,867			2,670			18		19
Expected return on plan assets		(4,039	)		(3,218	)		—		—
Amortization of actuarial loss		2,083			1,946			4		3
Net periodic benefit cost	$	4,154		$	3,937		$	22	$	22

		Pension Benefits
		Pension Plan						SERP
		Six months ended June 30,						Six months ended June 30,
		2013			2012			2013		2012
Components of net periodic benefit cost:
Service cost	$	6,414		$	5,105		$	—	$	—
Interest cost		5,702			5,254			35		37
Expected return on plan assets		(8,066	)		(6,438	)		—		—
Amortization of actuarial loss		4,139			3,698			9		7
Net periodic benefit cost	$	8,189		$	7,619		$	44	$	44

Other Postretirement Benefits [Member]

Defined Benefit Plan Disclosure [Line Items]

Components Of Net Periodic Benefit Cost

The components of net periodic benefit cost for the Company’s postretirement benefit plan for the three months and six months ended June 30, 2013 and 2012 were as follows (in thousands):

		Other Postretirement Benefits						Other Postretirement Benefits
		Postretirement Welfare Plan						Postretirement Welfare Plan
		Three months ended June 30,						Six months ended June 30,
		2013			2012			2013			2012
Components of net periodic benefit cost:
Service cost	$	—		$	—		$	—		$	—
Interest cost		28			34			56			67
Amortization of actuarial gain		(153	)		(156	)		(308	)		(310	)
Net periodic benefit cost	$	(125	)	$	(122	)	$	(252	)	$	(243	)

ACQUISITIONS (Details) (USD $)	3 Months Ended		6 Months Ended		0 Months Ended			0 Months Ended		0 Months Ended
ACQUISITIONS (Details) (USD $)	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 28, 2012 Flag Service & Maintenance, Inc. [Member]	Dec. 14, 2012 Penn Maritime Inc. and Maritime Investments LLC [Member] MMBbls	Dec. 14, 2012 Penn Maritime Inc. and Maritime Investments LLC [Member] Tugboats [Member]	Nov. 01, 2012 Allied Transportation Company [Member] bbl	Nov. 01, 2012 Allied Transportation Company [Member] Tank Barges [Member]	Nov. 01, 2012 Allied Transportation Company [Member] Offshore Dry Bulk Barges [Member] T	Nov. 01, 2012 Allied Transportation Company [Member] Coastal Tugboats [Member]
Business acquisition, consideration transferred [Abstract]
Cash consideration paid					$ 6,864,000	$ 146,750,000		$ 107,014,000
Total value of transaction						300,538,000
Stock consideration through issuance of Company common stock						29,080,000
Issue of common stock (in shares)						500,000
Shares issued per share (in dollars per share)						$ 58.16
Number of doubled hulled tank barges						18
Capacity, in barrels, of purchased productive assets (in barrels)						1.9		680,000
Number of productive assets purchased							16		10	3	7
Cash to retire outstanding debt						124,708,000
Capacity, in deadweight tons of purchased productive assets										48,000
Acquisition and integration related costs								10,000,000
Fair value of contingent earnout provision payable in 2014								9,756,000
Payment Of Contingent Liability	$ 5,000,000	$ 5,000,000	$ 5,000,000	$ 0

INVENTORIES (Details) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2013	Dec. 31, 2012
Details of inventories [Abstract]
Finished goods	$ 116,822	$ 162,859
Work in process	22,725	14,538
Inventory, Net, Total	$ 139,547	$ 177,397

FAIR VALUE MEASUREMENTS (Details) (USD $)	3 Months Ended		6 Months Ended			3 Months Ended	6 Months Ended		3 Months Ended	6 Months Ended
FAIR VALUE MEASUREMENTS (Details) (USD $)	Jun. 30, 2013	Mar. 31, 2013	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Allied Transportation Company [Member]	Jun. 30, 2013 Allied Transportation Company [Member]	Nov. 01, 2012 Allied Transportation Company [Member]	Jun. 30, 2013 United Holdings LLC [Member]	Jun. 30, 2013 United Holdings LLC [Member]	Apr. 15, 2011 United Holdings LLC [Member]	Jun. 30, 2013 Recurring [Member]	Dec. 31, 2012 Recurring [Member]	Jun. 30, 2013 Quoted Prices In Active Markets For Identical Assets (Level 1) Recurring [Member]	Dec. 31, 2012 Quoted Prices In Active Markets For Identical Assets (Level 1) Recurring [Member]	Jun. 30, 2013 Significant Other Observable Inputs (Level 2) Recurring [Member]	Dec. 31, 2012 Significant Other Observable Inputs (Level 2) Recurring [Member]	Jun. 30, 2013 Significant Unobservable Inputs (Level 3) Recurring [Member]	Dec. 31, 2012 Significant Unobservable Inputs (Level 3) Recurring [Member]
Assets [Abstract]
Derivatives												$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0	$ 0
Liabilities [Abstract]
Derivatives												30,000	1,525,000	0	0	30,000	1,525,000	0	0
Contingent liabilities												12,780,000	28,067,000	0	0	0	0	12,780,000	28,067,000
Liabilities fair value												12,810,000	29,592,000	0	0	30,000	1,525,000	12,780,000	28,067,000
Business Acquisition [Line Items]
Earnout Provision								10,000,000			50,000,000
Fair value contingent earn out liability						4,880,000	4,880,000	9,756,000	7,900,000	7,900,000	16,300,000
Payment of contingent liability	5,000,000	5,000,000	5,000,000	0
Increase (decrease) in fair value of contingent liability						14,000	113,000		6,100,000	10,400,000
Estimated fair value of outstanding debt	995,608,000		995,608,000		1,130,967,000
Carrying amount of debt	1,021,240,000		1,021,240,000		1,135,110,000
Impaired long-lived assets	$ 0

DERIVATIVE INSTRUMENTS (Fair Value of Derivative Instruments) (Details) (Designated as Hedging Instrument [Member], USD $)			3 Months Ended								3 Months Ended
	Jun. 30, 2013	Dec. 31, 2012	Jun. 30, 2013 Interest Rate Swap [Member]	Jun. 30, 2012 Interest Rate Swap [Member]	Jun. 30, 2013 Interest rate contract [Member] Other accrued liabilities [Member]	Dec. 31, 2012 Interest rate contract [Member] Other accrued liabilities [Member]	Jun. 30, 2013 Foreign currency contracts [Member] Other accrued liabilities [Member]	Dec. 31, 2012 Foreign currency contracts [Member] Other accrued liabilities [Member]	Jun. 30, 2013 Foreign currency contracts [Member] Other Long-Term Liabilities [Member]	Dec. 31, 2012 Foreign currency contracts [Member] Other Long-Term Liabilities [Member]	Jun. 30, 2013 Forward Contracts [Member]
Derivative instruments - risk management [Abstract]
Termination date			Feb. 28, 2013								Mar. 31, 2014
Notional amount				$ 200,000,000							$ 469,000
Derivative Instruments in Hedges, at Fair Value [Abstract]
Fair value, liability derivatives					0	1,486,000	30,000	0	0	39,000
Total derivatives designated as hedging instruments under ASC 815	30,000	1,525,000
Total liability derivatives	$ 30,000	$ 1,525,000

DERIVATIVE INSTRUMENTS (Cash Flow Hedges) (Details) (USD $)	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	$ 1,501,000	$ 1,670,000	$ 1,493,000	$ 3,872,000
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	(1,389,000)	(2,046,000)	(1,389,000)	(4,102,000)
Cash Flow Hedging [Member] \| Foreign exchange contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Loss expected to be reclassified from accumulated OCI into income effective portion over the next year			30,000
Cash Flow Hedging [Member] \| Foreign exchange contract [Member] \| Cost and sales of operating expenses [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	15,000	77,000	7,000	249,000
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	0	(2,000)	0	(2,000)
Cash Flow Hedging [Member] \| Interest rate contract [Member] \| Interest expense [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Amount of Gain (Loss) Recognized in OCI on Derivatives (Effective Portion)	1,486,000	1,593,000	1,486,000	3,623,000
Amount of Gain (Loss) Reclassified from Accumulated OCI into Income (Effective Portion)	$ (1,389,000)	$ (2,044,000)	$ (1,389,000)	$ (4,100,000)

STOCK AWARD PLANS (Details) (USD $)	3 Months Ended		6 Months Ended
STOCK AWARD PLANS (Details) (USD $)	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
STOCK AWARD PLANS [Abstract]
Compensation cost	$ 2,927,000	$ 2,583,000	$ 5,061,000	$ 4,489,000
Income tax benefit	1,106,000	987,000	1,913,000	1,715,000
Share based Compensation Plans Combined Disclosure [Abstract]
Intrinsic value of stock options exercised	3,342,000	1,612,000
Tax benefit from stock options exercised	1,263,000	616,000
Intrinsic value of restricted stock vestings	9,230,000	11,004,000
Tax benefit from restricted stock vesting	3,489,000	4,204,000
Unrecognized compensation cost related to unvested awards	4,720,000		4,720,000
Fair value of options vested	1,717,000	1,326,000
Fair value of restricted stock vested	9,230,000	11,004,000
Fair value of stock options granted (in dollars per share)	$ 25.07	$ 22.15
Fair value of stock options granted	4,125,000	3,461,000
Fair Value Assumptions [Abstract]
Dividend yield (in hundredths)		0.00%	0.00%
Average risk-free interest rate (in hundredths)		1.10%	1.10%
Stock price volatility (in hundredths)		33.00%	34.00%
Minimum [Member]
Fair Value Assumptions [Abstract]
Estimated option term			6 years	6 years
Maximum [Member]
Fair Value Assumptions [Abstract]
Estimated option term			7 years	7 years
Sixth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)			$ 75.17
Employee Stock Award Plan [Member]
Stock Award Plan Information [Abstract]
Shares available for future grants (in shares)	2,678,355		2,678,355
Elected director first grant vesting period	The options granted to a director when first elected vest immediately
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			351,173
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			109,560
Exercised, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			(43,449)
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)	417,284		417,284
Weighted Average Exercise Price [Abstract]
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share)			$ 46
Granted, Weighted Average Exercise Price (in dollars per share)			$ 71
Exercised, Weighted Average Exercise Price (in dollars per share)			$ 29
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share)	$ 54		$ 54
Unvested Restricted Stock Award Shares [Roll Forward]
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares (in shares)			418,128
Granted, Unvested Restricted Stock Award Shares (in shares)			128,125
Vested, Unvested Restricted Stock Award Shares (in shares)			(138,794)
Forfeited, Unvested Restricted Stock Award Shares (in shares)			(6,582)
Nonvested balance end of period, Unvested Restricted Stock Award Shares (in shares)	400,877		400,877
Weighted Average Grant Date Fair Value Per Share [Abstract]
Nonvested balance beginning of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 45.39
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 68.28
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 40.69
Forfeited, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 63.91
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share)	$ 54.03		$ 54.03
Employee Stock Award Plan [Member] \| First Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 32.56
Range of Exercise Prices, lower limit (in dollars per share)			$ 23.98
Options Outstanding [Abstract]
Number Outstanding (in shares)	93,249		93,249
Weighted Average Remaining Contractual Life (in years)			3 years 4 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 31.96		$ 31.96
Options Exercisable [Abstract]
Number Exercisable (in shares)	93,249		93,249
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 31.96		$ 31.96
Employee Stock Award Plan [Member] \| Second Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 36.35
Range of Exercise Prices, lower limit (in dollars per share)			$ 34.40
Options Outstanding [Abstract]
Number Outstanding (in shares)	14,000		14,000
Weighted Average Remaining Contractual Life (in years)			1 year 3 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 34.96		$ 34.96
Options Exercisable [Abstract]
Number Exercisable (in shares)	14,000		14,000
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 34.96		$ 34.96
Employee Stock Award Plan [Member] \| Third Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 46.74
Options Outstanding [Abstract]
Number Outstanding (in shares)	100,569		100,569
Weighted Average Remaining Contractual Life (in years)			4 years 7 months 6 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 46.74		$ 46.74
Options Exercisable [Abstract]
Number Exercisable (in shares)	67,039		67,039
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 46.74		$ 46.74
Employee Stock Award Plan [Member] \| Fourth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 70.65
Range of Exercise Prices, lower limit (in dollars per share)			$ 65.28
Options Outstanding [Abstract]
Number Outstanding (in shares)	209,466		209,466
Weighted Average Remaining Contractual Life (in years)			6 years 1 month 6 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 68.34		$ 68.34
Options Exercisable [Abstract]
Number Exercisable (in shares)	33,299		33,299
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 65.8		$ 65.8
Employee Stock Award Plan [Member] \| Full Exercise Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 70.65
Range of Exercise Prices, lower limit (in dollars per share)			$ 23.98
Options Outstanding [Abstract]
Number Outstanding (in shares)	417,284		417,284
Weighted Average Remaining Contractual Life (in years)			5 years
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 53.88		$ 53.88
Aggregate Intrinsic Value, Options Outstanding	10,706,000		10,706,000
Options Exercisable [Abstract]
Number Exercisable (in shares)	207,587		207,587
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 42.36		$ 42.36
Aggregate Intrinsic Value, Options Exercisable	7,717,000		7,717,000
2000 Director Plan [Member]
Stock Award Plan Information [Abstract]
Term of grant	10 years
Shares available for future grants (in shares)	610,041		610,041
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			345,938
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			54,958
Exercised, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)			(36,000)
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares)	364,896		364,896
Weighted Average Exercise Price [Abstract]
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share)			$ 45.84
Granted, Weighted Average Exercise Price (in dollars per share)			$ 75.17
Exercised, Weighted Average Exercise Price (in dollars per share)			$ 36.79
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share)	$ 51.15		$ 51.15
Unvested Restricted Stock Award Shares [Roll Forward]
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares (in shares)			348
Granted, Unvested Restricted Stock Award Shares (in shares)			10,536
Vested, Unvested Restricted Stock Award Shares (in shares)			(732)
Nonvested balance end of period, Unvested Restricted Stock Award Shares (in shares)	10,152		10,152
Weighted Average Grant Date Fair Value Per Share [Abstract]
Nonvested balance beginning of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 62.99
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 75.65
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share)			$ 69.63
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share)	$ 75.65		$ 75.65
2000 Director Plan [Member] \| First Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, lower limit (in dollars per share)			$ 17.88
Options Outstanding [Abstract]
Number Outstanding (in shares)	12,000		12,000
Weighted Average Remaining Contractual Life (in years)			9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 17.88		$ 17.88
Options Exercisable [Abstract]
Number Exercisable (in shares)	12,000		12,000
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 17.88		$ 17.88
2000 Director Plan [Member] \| Second Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 29.60
Range of Exercise Prices, lower limit (in dollars per share)			$ 20.28
Options Outstanding [Abstract]
Number Outstanding (in shares)	36,000		36,000
Weighted Average Remaining Contractual Life (in years)			4 years 6 months
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 26.49		$ 26.49
Options Exercisable [Abstract]
Number Exercisable (in shares)	36,000		36,000
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 26.49		$ 26.49
2000 Director Plan [Member] \| Third Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 36.82
Range of Exercise Prices, lower limit (in dollars per share)			$ 35.17
Options Outstanding [Abstract]
Number Outstanding (in shares)	56,036		56,036
Weighted Average Remaining Contractual Life (in years)			3 years 3 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 35.91		$ 35.91
Options Exercisable [Abstract]
Number Exercisable (in shares)	56,036		56,036
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 35.91		$ 35.91
2000 Director Plan [Member] \| Fourth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 56.45
Range of Exercise Prices, lower limit (in dollars per share)			$ 41.24
Options Outstanding [Abstract]
Number Outstanding (in shares)	145,596		145,596
Weighted Average Remaining Contractual Life (in years)			6 years 6 months
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 52.14		$ 52.14
Options Exercisable [Abstract]
Number Exercisable (in shares)	145,596		145,596
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 52.14		$ 52.14
2000 Director Plan [Member] \| Fifth Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 62.48
Range of Exercise Prices, lower limit (in dollars per share)			$ 61.89
Options Outstanding [Abstract]
Number Outstanding (in shares)	60,306		60,306
Weighted Average Remaining Contractual Life (in years)			8 years 10 months 24 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 62.38		$ 62.38
Options Exercisable [Abstract]
Number Exercisable (in shares)	60,306		60,306
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 62.38		$ 62.38
2000 Director Plan [Member] \| Sixth Price Range [Member]
Options Outstanding [Abstract]
Number Outstanding (in shares)	54,958		54,958
Weighted Average Remaining Contractual Life (in years)			9 years 9 months 18 days
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 75.17		$ 75.17
Options Exercisable [Abstract]
Number Exercisable (in shares)	239		239
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 75.17		$ 75.17
2000 Director Plan [Member] \| Full Exercise Price Range [Member]
Outstanding and Exercisable Stock options [Abstract]
Range of Exercise Prices, upper limit (in dollars per share)			$ 75.17
Range of Exercise Prices, lower limit (in dollars per share)			$ 17.88
Options Outstanding [Abstract]
Number Outstanding (in shares)	364,896		364,896
Weighted Average Remaining Contractual Life (in years)			6 years 6 months
Weighted Average Exercise Price, Options Outstanding (in dollars per share)	$ 51.15		$ 51.15
Aggregate Intrinsic Value, Options Outstanding	10,358,000		10,358,000
Options Exercisable [Abstract]
Number Exercisable (in shares)	310,177		310,177
Weighted Average Exercise Price, Options Exercisable (in dollars per share)	$ 46.92		$ 46.92
Aggregate Intrinsic Value, Options Exercisable	10,119,000		10,119,000
Employee Stock Award Plan - Options Granted After to January 25, 2010 [Member]
Stock Award Plan Information [Abstract]
Term of grant	7 years
Vesting period	3 years
Employee Stock Award Plan - Options Granted Prior to January 25, 2010 [Member]
Stock Award Plan Information [Abstract]
Term of grant	5 years
Vesting period	3 years
Stock Options [Member]
Share based Compensation Plans Combined Disclosure [Abstract]
Weighted average period of recognition in years			1 year 6 months
Restricted Stock [Member]
Share based Compensation Plans Combined Disclosure [Abstract]
Unrecognized compensation cost related to unvested awards		$ 19,325,000		$ 19,325,000
Weighted average period of recognition in years			3 years 1 month 6 days

OTHER COMPREHENSIVE INCOME (Details) (USD $)
In Thousands, unless otherwise specified

3 Months Ended

6 Months Ended

Jun. 30, 2013

Jun. 30, 2012

Jun. 30, 2013

Jun. 30, 2012

Pension and postretirement benefits [Abstract]

Amortization of net actuarial loss, Gross Amount

$ 1,934

^[1]

$ 1,794

^[1]

$ 3,840

^[1]

$ 3,395

^[1]

Amortization of net actuarial loss, Income Tax (Provision) Benefit

(740)

^[1]

(704)

^[1]

(1,469)

^[1]

(1,316)

^[1]

Amortization of net actuarial loss, Net Amount

1,194

^[1]

1,090

^[1]

2,371

^[1]

2,079

^[1]

Actuarial gains, Gross Amount

(1,134)

^[1]

(3,851)

^[1]

(1,134)

^[1]

(3,851)

^[1]

Actuarial gains, Income Tax (Provision) Benefit

434

^[1]

1,493

^[1]

434

^[1]

1,493

^[1]

Actuarial gains, Net Amount

(700)

^[1]

(2,358)

^[1]

(700)

^[1]

(2,358)

^[1]

Foreign currency translation adjustments, Gross Amount

^[1]

152

^[1]

249

^[1]

447

^[1]

Foreign currency translation adjustments, Income Tax (Provision) Benefit

^[1]

Foreign currency translation adjustments, Net Amount

^[1]

152

^[1]

249

^[1]

447

^[1]

Change in fair value of derivative instruments [Abstract]

Unrealized gains (losses), Gross Amount

(7)

^[2]

4,258

^[2]

2,882

^[2]

7,974

^[2]

Unrealized gains, Income Tax (Provision) Benefit

(3)

^[2]

(1,520)

^[2]

(1,009)

^[2]

(2,826)

^[2]

Unrealized gains, Net Amount

(4)

^[2]

2,738

^[2]

1,873

^[2]

5,148

^[2]

Reclassified to net earnings, Gross Amount

^[2]

(2,056)

^[2]

(1,389)

^[2]

(4,102)

^[2]

Reclassified to net earnings, Income Tax (Provision) Benefit

^[2]

738

^[2]

486

^[2]

1,454

^[2]

Reclassified to net earnings, Net Amount

^[2]

(1,318)

^[2]

(903)

^[2]

(2,648)

^[2]

Total other comprehensive income (loss), Gross Amount

837

^[2]

297

^[2]

4,448

^[2]

3,863

^[2]

Total other comprehensive income (loss), Income Tax (Provision) Benefit

(303)

^[2]

(1,558)

^[2]

(1,195)

^[2]

Total comprehensive income (loss), net of taxes

$ 534

^[2]

$ 304

^[2]

$ 2,890

^[2]

$ 2,668

^[2]

[1]	Actuarial gains (losses) are amortized into costs of sales and operating expenses or selling, general and administrative expenses as appropriate. (See Note 12 – Retirement Plans)
[2]	Reclassifications to net earnings of derivatives qualifying as effective hedges are recognized in interest expense or costs of sales and operating expenses as appropriate. (See Note 6 – Derivative Instruments)

SEGMENT DATA (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013 Segment	Jun. 30, 2012	Dec. 31, 2012
SEGMENT DATA [Abstract]
Number of Reportable Segments			2
Revenues [Abstract]
Marine transportation	$ 423,868	$ 342,195	$ 842,386	$ 678,152
Diesel engine services	140,040	169,653	280,307	400,631
Total revenues	563,908	511,848	1,122,693	1,078,783
Segment profit (loss)	102,134	77,827	194,070	161,196
Total assets	3,724,309		3,724,309		3,653,128
Other segment disclosures [Abstract]
Loss on disposition of assets	537	69	505	41
Interest expense	(7,219)	(5,901)	(15,207)	(11,741)
Other income	101	30	176	179
Details of "Other" total assets [Abstract]
Total assets	3,724,309		3,724,309		3,653,128
Marine transportation [Member]
Revenues [Abstract]
Marine transportation	97,563	71,730	186,816	140,220
Total assets	3,054,231		3,054,231		2,951,723
Details of "Other" total assets [Abstract]
Total assets	3,054,231		3,054,231		2,951,723
Diesel engine services [Member]
Revenues [Abstract]
Diesel engine services	14,932	15,118	28,954	38,672
Total assets	616,496		616,496		647,986
Details of "Other" total assets [Abstract]
Total assets	616,496		616,496		647,986
Other [Member]
Revenues [Abstract]
Segment profit (loss)	(10,361)	(9,021)	(21,700)	(17,696)
Total assets	53,582		53,582		53,419
Other segment disclosures [Abstract]
General corporate expenses	(3,780)	(3,219)	(7,174)	(6,175)
Loss on disposition of assets	537	69	505	41
Interest expense	(7,219)	(5,901)	(15,207)	(11,741)
Other income	101	30	176	179
Profit (loss) from other segment	(10,361)	(9,021)	(21,700)	(17,696)
Details of "Other" total assets [Abstract]
General corporate assets	51,574		51,574		51,611
Investment in affiliates	2,008		2,008		1,808
Total assets	$ 53,582		$ 53,582		$ 53,419

TAXES ON INCOME (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
TAXES ON INCOME [Abstract]
Earnings before taxes on income - United States	$ 102,134	$ 77,827	$ 194,070	$ 161,196
Federal [Abstract]
Current	8,102	10,416	17,532	20,096
Deferred	26,386	15,591	47,883	33,774
State and local	3,854	3,385	7,311	7,012
Total Provision for taxes on income	$ 38,342	$ 29,392	$ 72,726	$ 60,882

EARNINGS PER SHARE (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
EARNINGS PER SHARE [Abstract]
Net earnings attributable to Kirby	$ 63,093	$ 47,551	$ 119,671	$ 98,495
Undistributed earnings allocated to restricted shares	(459)	(375)	(859)	(769)
Income available to Kirby common stockholders - basic	62,634	47,176	118,812	97,726
Undistributed earnings allocated to restricted shares	459	375	859	769
Undistributed earnings reallocated to restricted shares	(457)	(374)	(856)	(765)
Income available to Kirby common stockholders - diluted	$ 62,636	$ 47,177	$ 118,815	$ 97,730
Shares outstanding [Abstract]
Weighted average common stock issued and outstanding (in shares)	56,752,000	55,869,000	56,712,000	55,839,000
Weighted average unvested restricted stock (in shares)	(413,000)	(441,000)	(407,000)	(436,000)
Weighted average common stock outstanding - basic (in shares)	56,339,000	55,428,000	56,305,000	55,403,000
Dilutive effect of stock options (in shares)	190,000	212,000	188,000	235,000
Weighted average common stock outstanding - diluted (in shares)	56,529,000	55,640,000	56,493,000	55,638,000
Net earnings per share attributable to Kirby common stockholders:
Basic (in dollars per share)	$ 1.11	$ 0.85	$ 2.11	$ 1.76
Diluted (in dollars per share)	$ 1.11	$ 0.85	$ 2.10	$ 1.76
Antidilutive Securities Excluded from Computation of Earnings Per Share (in shares)	165,000	157,000

RETIREMENT PLANS (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Pension Plan [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	$ 3,243	$ 2,539	$ 6,414	$ 5,105
Interest cost	2,867	2,670	5,702	5,254
Expected return on plan assets	(4,039)	(3,218)	(8,066)	(6,438)
Amortization of actuarial gain	2,083	1,946	4,139	3,698
Net periodic benefit cost	4,154	3,937	8,189	7,619
SERP [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0	0	0
Interest cost	18	19	35	37
Expected return on plan assets	0	0	0	0
Amortization of actuarial gain	4	3	9	7
Net periodic benefit cost	22	22	44	44
Other Postretirement Benefits [Member]
Components of net periodic benefit cost: [Abstract]
Service cost	0	0	0	0
Interest cost	28	34	56	67
Amortization of actuarial gain	(153)	(156)	(308)	(310)
Net periodic benefit cost	$ (125)	$ (122)	$ (252)	$ (243)

CONTINGENCIES (Details) (USD $)	6 Months Ended
CONTINGENCIES (Details) (USD $)	Jun. 30, 2013
Guarantor Obligations [Line Items]
Issued guaranties	$ 45,818,000
Guarantor obligations, term	All of these instruments have an expiration date within five years
Expiration period for instruments under contingencies, maximum	5 years
Performance Bonds [Member]
Guarantor Obligations [Line Items]
Issued guaranties	39,690,000
Standby Letters Of Credit [Member]
Guarantor Obligations [Line Items]
Issued guaranties	$ 6,128,000
Gulfco Marine Superfund Site [Member]
Site Contingency [Line Items]
Number of other companies also named as Potentially Responsible Parties ("PRPs")	3
Number of companies named as Potentially Responsible Parties ("PRPs")	5
Palmer Barge Line Superfund Site [Member]
Site Contingency [Line Items]
Number of other companies also named as Potentially Responsible Parties ("PRPs")	45