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STOCK AWARD PLANS (Details) (USD $)
3 Months Ended
Mar. 31, 2015
Mar. 31, 2014
STOCK AWARD PLANS [Abstract]    
Compensation cost $ 2,538,000us-gaap_AllocatedShareBasedCompensationExpense $ 2,153,000us-gaap_AllocatedShareBasedCompensationExpense
Income tax benefit 949,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense 816,000us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense
Share based Compensation Plans Combined Disclosure [Abstract]    
Intrinsic value of stock options exercised 68,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue 6,102,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Tax benefit from stock options exercised 26,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised 2,313,000us-gaap_DeferredTaxExpenseFromStockOptionsExercised
Intrinsic value of restricted stock vesting 8,986,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue 13,916,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue
Tax benefit from restricted stock vesting 3,361,000kex_TaxBenefitFromRestrictedStockVesting 5,274,000kex_TaxBenefitFromRestrictedStockVesting
Fair value of options vested 2,167,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue 2,076,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue
Fair value of restricted stock vested 8,986,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue 13,916,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Fair value of stock options granted (in dollars per share) $ 25.18kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue $ 34.20kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue
Fair value of stock options granted 2,893,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue 2,503,000kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue
Fair Value Assumptions [Abstract]    
Dividend yield (in hundredths) 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate 0.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
Average risk-free interest rate (in hundredths) 1.30%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate 1.80%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
Stock price volatility (in hundredths) 33.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate 33.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
Estimated option term 6 years 6 years
Employee Stock Award Plan [Member]    
Stock Award Plan Information [Abstract]    
Shares available for future grants (in shares) 2,304,182us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]    
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 322,956us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 114,894us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 437,850us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Weighted Average Exercise Price [Abstract]    
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share) $ 69.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Granted, Weighted Average Exercise Price (in dollars per share) $ 74.99us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share) $ 71.27us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Unvested Restricted Stock Award Shares [Roll Forward]    
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares (in shares) 321,453us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Granted, Unvested Restricted Stock Award Shares (in shares) 121,870us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Vested, Unvested Restricted Stock Award Shares (in shares) (113,383)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Nonvested balance end of period, Unvested Restricted Stock Award Shares (in shares) 329,940us-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 (in dollars per share) $ 71.04us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 75.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 60.72us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
 
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 76.05us-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) 1 year 10 months 24 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, lower limit (in dollars per share) $ 46.74us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ 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) 2 years 9 months 18 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) $ 74.99us-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) 287,140us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
 
Weighted Average Remaining Contractual Life (in years) 3 years 9 months 18 days  
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 71.03us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
 
Options Exercisable [Abstract]    
Number Exercisable (in shares) 141,669us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_ThirdPriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 67.90us-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) 5 years 9 months 18 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) 12,576us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 93.89us-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) 5 years 10 months 24 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) 12,476us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FifthPriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 102.53us-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) 437,850us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Weighted Average Remaining Contractual Life (in years) 4 years  
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 71.27us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Aggregate Intrinsic Value, Options Outstanding 3,472,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Options Exercisable [Abstract]    
Number Exercisable (in shares) 240,260us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 63.60us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_EmployeePlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Aggregate Intrinsic Value, Options Exercisable 3,330,000us-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
 
Outstanding Non-Qualified or Nonincentive Stock Awards [Roll Forward]    
Outstanding at Period Start, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 298,334us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Exercised, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) (6,000)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Outstanding at Period End, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) 292,334us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Weighted Average Exercise Price [Abstract]    
Outstanding at Period Start, Weighted Average Exercise Price (in dollars per share) $ 60.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Exercised, Weighted Average Exercise Price (in dollars per share) $ 62.48us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Outstanding at Period End, Weighted Average Exercise Price (in dollars per share) $ 59.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Unvested Restricted Stock Award Shares [Roll Forward]    
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares (in shares) 292us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Vested, Unvested Restricted Stock Award Shares (in shares) (292)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Nonvested balance end of period, Unvested Restricted Stock Award Shares (in shares) 0us-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 (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 99.52us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
 
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share (in dollars per share) $ 0us-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 8 months 12 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  
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  
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) 48,306us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
 
Weighted Average Remaining Contractual Life (in years) 6 years 2 months 12 days  
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 62.36us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
 
Options Exercisable [Abstract]    
Number Exercisable (in shares) 48,306us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_FourthPriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 62.36us-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) 6 years 10 months 24 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] | Full Exercise 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_TotalExercisePriceRangeMember
 
Range of Exercise Prices, lower limit (in dollars per share) $ 20.28us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Options Outstanding [Abstract]    
Number Outstanding (in shares) 292,334us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfOutstandingOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Weighted Average Remaining Contractual Life (in years) 4 years 8 months 12 days  
Weighted Average Exercise Price, Options Outstanding (in dollars per share) $ 59.95us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Aggregate Intrinsic Value, Options Outstanding 5,446,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Options Exercisable [Abstract]    
Number Exercisable (in shares) 292,334us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Weighted Average Exercise Price, Options Exercisable (in dollars per share) $ 59.95us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
Aggregate Intrinsic Value, Options Exercisable 5,446,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_PlanNameAxis
= kex_DirectorPlanMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= kex_TotalExercisePriceRangeMember
 
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  
Stock Options [Member]    
Share based Compensation Plans Combined Disclosure [Abstract]    
Unrecognized compensation cost related to unvested awards 4,981,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
 
Weighted average period of recognition in years 2 years  
Restricted Stock [Member]    
Share based Compensation Plans Combined Disclosure [Abstract]    
Unrecognized compensation cost related to unvested awards $ 23,486,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
 
Weighted average period of recognition in years 3 years 6 months