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Stock Award Plans (Details) (USD $)
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Stock Award Plans [Abstract]      
Compensation cost $ 11,591,000us-gaap_AllocatedShareBasedCompensationExpense $ 11,621,000us-gaap_AllocatedShareBasedCompensationExpense $ 9,796,000us-gaap_AllocatedShareBasedCompensationExpense
Income tax benefit 4,358,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 4,370,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 3,644,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Stock Award Plan Information [Abstract]      
Term of grant 7 years    
Vesting period 3 years    
Share-based Compensation Plans Combined Disclosure [Abstract]      
Intrinsic value of stock options exercised 11,671,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue 6,703,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue 6,768,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Tax benefit from stock options exercised 4,388,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised 2,520,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised 2,518,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised
Intrinsic value of restricted stock vestings 14,847,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue 10,993,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue 11,878,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue
Tax benefit from restricted stock vesting 5,583,000kex_TaxBenefitFromRestrictedStockVesting 4,133,000kex_TaxBenefitFromRestrictedStockVesting 4,418,000kex_TaxBenefitFromRestrictedStockVesting
Fair value of options vested 3,759,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue 3,341,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue 2,846,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue
Fair value of restricted stock vested 14,847,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue 10,993,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue 11,878,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Fair value of stock options granted (in dollars per share) $ 36.05kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue $ 25.14kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue $ 22.21kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue
Fair value of stock options granted 4,226,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue 4,184,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue 3,691,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue
Employee Stock Award Plan [Member]      
Stock Award Plan Information [Abstract]      
Shares available for future grants (in shares) 2,540,946us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
   
Elected director first grant vesting period The options granted when first elected a director vest immediately    
Options Exercisable [Abstract]      
Stock options exercisable 157,140us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
175,170us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
149,544us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Unvested Restricted Stock Award Shares [Roll Forward]      
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares 399,278us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
418,128us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
475,632us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Granted, Unvested Restricted Stock Award Shares (in shares) 97,706us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
139,971us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
121,953us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Vested, Unvested Restricted Stock Award Shares (in shares) (141,870)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(149,162)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(168,166)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Forfeited, Unvested Restricted Stock Award Shares (in shares) (33,661)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(9,659)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(11,291)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Nonvested balance end of period, Unvested Restricted Stock Award Shares 321,453us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
399,278us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
418,128us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Weighted Average Grant Date Fair Value Per Share [Abstract]      
Nonvested balance beginning of period, Weighted Average Grant Date Fair Value Per Share $ 54.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 45.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 36.43us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 97.46us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 69.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 67.79us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 45.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 44.30us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 35.43us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Forfeited, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 63.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 61.20us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 58.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share $ 71.04us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 54.92us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 45.39us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
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) $ 36.35us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 31.35us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 16,910us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 2 years 1 month 6 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 32.82us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 16,910us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 32.82us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
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) $ 46.74us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 56,629us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 3 years 1 month 6 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 46.74us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 56,629us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 46.74us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
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) $ 70.65us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 65.28us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 172,246us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 4 years 7 months 6 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 68.39us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 82,946us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 67.56us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
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) $ 96.85us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 86.96us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 37,730us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 6 years 1 month 6 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 93.89us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 655us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 86.96us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Employee Stock Award Plan [Member] | Fifth Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 114.11us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 101.46us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 39,441us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 6 years 2 months 12 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 103.12us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 0us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 0us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
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) $ 114.11us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 31.35us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 322,956us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 4 years 7 months 6 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 69.95us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Aggregate Intrinsic Value, Options Outstanding 4,863,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 157,140us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 56.40us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Aggregate Intrinsic Value, Options Exercisable 3,829,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
2000 Director Plan [Member]      
Stock Award Plan Information [Abstract]      
Term of grant 10 years    
Vesting period 6 months    
Shares available for future grants (in shares) 559,881us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
   
Options Exercisable [Abstract]      
Stock options exercisable 298,334us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
320,082us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
345,360us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Unvested Restricted Stock Award Shares [Roll Forward]      
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares 384us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
348us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
1,748us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Granted, Unvested Restricted Stock Award Shares (in shares) 8,160us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
10,536us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
10,383us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Vested, Unvested Restricted Stock Award Shares (in shares) (8,252)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
(10,500)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
(11,783)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Nonvested balance end of period, Unvested Restricted Stock Award Shares 292us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
384us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
348us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Weighted Average Grant Date Fair Value Per Share [Abstract]      
Nonvested balance beginning of period, Weighted Average Grant Date Fair Value Per Share $ 75.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 62.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 58.07us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 75.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 62.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 98.41us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 75.23us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 62.26us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share $ 99.52us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 75.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 62.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
2000 Director Plan [Member] | First Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 29.60us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 20.28us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 30,000us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 1 year 10 months 24 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 25.87us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 30,000us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 25.87us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FirstPriceRangeMember
   
2000 Director Plan [Member] | Second Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 36.82us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 35.17us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 32,048us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 1 year 3 months 18 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 36.09us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 32,048us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 36.09us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SecondPriceRangeMember
   
2000 Director Plan [Member] | Third Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 56.45us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 41.24us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 91,022us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 4 years 2 months 12 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 51.87us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 91,022us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 51.87us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
   
2000 Director Plan [Member] | Fourth Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 62.48us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 61.89us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 54,306us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 5 years 9 months 18 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 62.37us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 54,306us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 62.37us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
   
2000 Director Plan [Member] | Fifth Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 75.17us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Options Outstanding [Abstract]      
Number Outstanding (in shares) 90,958us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 7 years 2 months 12 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 86.41us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 90,958us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 86.41us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
   
2000 Director Plan [Member] | Sixth Price Range [Member]      
Outstanding and Exercisable Stock options [Abstract]      
Range of Exercise Prices, upper limit (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SixthPriceRangeMember
   
Range of Exercise Prices, lower limit (in dollars per share) $ 20.28us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_SixthPriceRangeMember
   
2000 Director Plan [Member] | Full Exercise Price Range [Member]      
Options Outstanding [Abstract]      
Number Outstanding (in shares) 298,334us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Weighted Average Remaining Contractual Life (in years) 4 years 10 months 24 days    
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 60.01us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Aggregate Intrinsic Value, Options Outstanding 6,975,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Options Exercisable [Abstract]      
Number Exercisable (in shares) 298,334us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 60.01us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Aggregate Intrinsic Value, Options Exercisable 6,975,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
   
Stock Options [Member]      
Share-based Compensation Plans Combined Disclosure [Abstract]      
Unrecognized compensation cost related to unvested awards 2,701,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
   
Weighted average period of recognition in years 1 year 2 months 12 days    
Fair Value Assumptions [Abstract]      
Dividend yield (in hundredths) 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Average risk-free interest rate (in hundredths) 2.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1.10%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Stock price volatility (in hundredths) 33.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
34.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
33.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Stock Options [Member] | Minimum [Member]      
Fair Value Assumptions [Abstract]      
Estimated option term (in years) 6 years 6 years 6 years
Stock Options [Member] | Maximum [Member]      
Fair Value Assumptions [Abstract]      
Estimated option term (in years) 7 years 7 years 7 years
Stock Options [Member] | Employee Stock Award Plan [Member]      
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]      
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 379,604us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
351,173us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
445,674us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 75,204us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
111,527us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
99,906us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Exercised, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) (119,276)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(83,096)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(191,955)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Canceled or expired, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) (12,576)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
(2,452)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 322,956us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
379,604us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
351,173us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Weighted Average Exercise Price [Abstract]      
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share) $ 55.42us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 45.54us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 36.81us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Granted, Weighted Average Exercise Price (in dollars per share) $ 98.91us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 70.94us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 65.80us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Exercised, Weighted Average Exercise Price (in dollars per share) $ 42.07us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 34.51us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 35.65us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Canceled or expired, Weighted Average Exercise Price (in dollars per share) $ 68.89us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 0us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 58.28us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share) $ 69.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 55.42us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
$ 45.54us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
Stock Options [Member] | 2000 Director Plan [Member]      
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]      
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 320,322us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
345,938us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
353,625us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 42,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
54,958us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
66,306us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Exercised, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) (63,988)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
(80,574)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
(73,993)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 298,334us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
320,322us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
345,938us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Weighted Average Exercise Price [Abstract]      
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share) $ 50.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 45.84us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 39.05us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Granted, Weighted Average Exercise Price (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 75.17us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 62.39us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Exercised, Weighted Average Exercise Price (in dollars per share) $ 39.08us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 46.75us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 28.22us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share) $ 60.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 50.64us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
$ 45.84us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
Restricted Stock [Member]      
Share-based Compensation Plans Combined Disclosure [Abstract]      
Unrecognized compensation cost related to unvested awards $ 16,271,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
   
Weighted average period of recognition in years 2 years 7 months 6 days