Document and Entity Information - shares
9 Months Ended
Sep. 30, 2019
Nov. 06, 2019
Cover [Abstract]    
Entity Registrant Name KIRBY CORP  
Entity Central Index Key 0000056047  
Current Fiscal Year End Date --12-31  
Entity Current Reporting Status Yes  
Entity Interactive Data Current Yes  
Entity Shell Company false  
Entity Filer Category Large Accelerated Filer  
Entity Small Business false  
Entity Emerging Growth Company false  
Entity Common Stock, Shares Outstanding   59,947,000
Document Type 10-Q  
Amendment Flag false  
Document Period End Date Sep. 30, 2019  
Document Fiscal Year Focus 2019  
Document Fiscal Period Focus Q3  
Document Quarterly Report true  
Document Transition Report false  
Entity File Number 1-7615  
Entity Tax Identification Number 74-1884980  
Entity Incorporation, State or Country Code NV  
Entity Address, Address Line One 55 Waugh Drive, Suite 1000  
Entity Address, City or Town Houston  
Entity Address, State or Province TX  
Entity Address, Postal Zip Code 77007  
City Area Code 713  
Local Phone Number 435-1000  
Title of 12(b) Security Common Stock  
Trading Symbol KEX  
Security Exchange Name NYSE