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Stock Award Plans (Details) (USD $) | 12 Months Ended
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Dec. 31, 2014 | Dec. 31, 2013 | Dec. 31, 2012
Stock Award Plans [Abstract] |  |  |
Compensation cost | $ 11,591,000 us-gaap_AllocatedShareBasedCompensationExpense | $ 11,621,000 us-gaap_AllocatedShareBasedCompensationExpense | $ 9,796,000 us-gaap_AllocatedShareBasedCompensationExpense
Income tax benefit | 4,358,000 us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense | 4,370,000 us-gaap_EmployeeServiceShareBasedCompensationTaxBenefitFromCompensationExpense | 3,644,000 us-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 | 11,671,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue | 6,703,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue | 6,768,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
Tax benefit from stock options exercised | 4,388,000 us-gaap_DeferredTaxExpenseFromStockOptionsExercised | 2,520,000 us-gaap_DeferredTaxExpenseFromStockOptionsExercised | 2,518,000 us-gaap_DeferredTaxExpenseFromStockOptionsExercised
Intrinsic value of restricted stock vestings | 14,847,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue | 10,993,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue | 11,878,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalIntrinsicValue
Tax benefit from restricted stock vesting | 5,583,000 kex_TaxBenefitFromRestrictedStockVesting | 4,133,000 kex_TaxBenefitFromRestrictedStockVesting | 4,418,000 kex_TaxBenefitFromRestrictedStockVesting
Fair value of options vested | 3,759,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue | 3,341,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue | 2,846,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedInPeriodTotalFairValue
Fair value of restricted stock vested | 14,847,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue | 10,993,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue | 11,878,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodTotalFairValue
Fair value of stock options granted (in dollars per share) | $ 36.05 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue | $ 25.14 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue | $ 22.21 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageFairValue
Fair value of stock options granted | 4,226,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue | 4,184,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue | 3,691,000 kex_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodFairValue
Employee Stock Award Plan [Member] |  |  |
Stock Award Plan Information [Abstract] |  |  |
Shares available for future grants (in shares) | 2,540,946 us-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 | 157,140 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 175,170 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 149,544 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Unvested Restricted Stock Award Shares [Roll Forward] |  |  |
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares | 399,278 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 418,128 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 475,632 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Granted, Unvested Restricted Stock Award Shares (in shares) | 97,706 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 139,971 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 121,953 us-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 | 321,453 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 399,278 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 418,128 us-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 | $ 54.92 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 45.39 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 36.43 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share) | $ 97.46 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 69.85 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 67.79 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) | $ 45.64 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 44.30 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 35.43 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Forfeited, Weighted Average Grant Date Fair Value Per Share (in dollars per share) | $ 63.56 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 61.20 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 58.64 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share | $ 71.04 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 54.92 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 45.39 us-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) | $ 36.35 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 31.35 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 16,910 us-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) | $ 32.82 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 16,910 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 32.82 us-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) | $ 46.74 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 56,629 us-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) | $ 46.74 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 56,629 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 46.74 us-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) | $ 70.65 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 65.28 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 172,246 us-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) | $ 68.39 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 82,946 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 67.56 us-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) | $ 96.85 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 86.96 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 37,730 us-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) | $ 93.89 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 655 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 86.96 us-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) | $ 114.11 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 101.46 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 39,441 us-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) | $ 103.12 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 0 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 0 us-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) | $ 114.11 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 31.35 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 322,956 us-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) | $ 69.95 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Aggregate Intrinsic Value, Options Outstanding | 4,863,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 157,140 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 56.40 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_PlanNameAxis = kex_EmployeePlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Aggregate Intrinsic Value, Options Exercisable | 3,829,000 us-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) | 559,881 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNumberOfSharesAvailableForGrant / us-gaap_PlanNameAxis = kex_DirectorPlanMember |  |
Options Exercisable [Abstract] |  |  |
Stock options exercisable | 298,334 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 320,082 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 345,360 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisableNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Unvested Restricted Stock Award Shares [Roll Forward] |  |  |
Nonvested balance beginning of period, Unvested Restricted Stock Award Shares | 384 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 348 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 1,748 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Granted, Unvested Restricted Stock Award Shares (in shares) | 8,160 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 10,536 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 10,383 us-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 | 292 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 384 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 348 us-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 | $ 75.65 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 62.99 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 58.07 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Granted, Weighted Average Grant Date Fair Value Per Share (in dollars per share) | $ 99.52 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 75.65 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 62.99 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Vested, Weighted Average Grant Date Fair Value Per Share (in dollars per share) | $ 98.41 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 75.23 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 62.26 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Nonvested balance end of period, Weighted Average Grant Date Fair Value Per Share | $ 99.52 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 75.65 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 62.99 us-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) | $ 29.60 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 20.28 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 30,000 us-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) | $ 25.87 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 30,000 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FirstPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 25.87 us-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) | $ 36.82 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 35.17 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 32,048 us-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) | $ 36.09 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 32,048 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SecondPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 36.09 us-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) | $ 56.45 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 41.24 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 91,022 us-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) | $ 51.87 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 91,022 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_ThirdPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 51.87 us-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) | $ 62.48 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 61.89 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 54,306 us-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) | $ 62.37 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 54,306 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FourthPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 62.37 us-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) | $ 99.52 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 75.17 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeLowerRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Options Outstanding [Abstract] |  |  |
Number Outstanding (in shares) | 90,958 us-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) | $ 86.41 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 90,958 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_FifthPriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 86.41 us-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) | $ 99.52 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeUpperRangeLimit / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_SixthPriceRangeMember |  |
Range of Exercise Prices, lower limit (in dollars per share) | $ 20.28 us-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) | 298,334 us-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) | $ 60.01 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeOutstandingOptionsWeightedAverageExercisePriceBeginningBalance1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Aggregate Intrinsic Value, Options Outstanding | 6,975,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Options Exercisable [Abstract] |  |  |
Number Exercisable (in shares) | 298,334 us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeNumberOfExercisableOptions / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Weighted Average Exercise Price, Options Exercisable (in dollars per share) | $ 60.01 us-gaap_SharebasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeExercisableOptionsWeightedAverageExercisePrice1 / us-gaap_PlanNameAxis = kex_DirectorPlanMember / us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis = kex_TotalExercisePriceRangeMember |  |
Aggregate Intrinsic Value, Options Exercisable | 6,975,000 us-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 | 2,701,000 us-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) | 379,604 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 351,173 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 445,674 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) | 75,204 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 111,527 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 99,906 us-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 | 0 us-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) | 322,956 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 379,604 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | 351,173 us-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) | $ 55.42 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 45.54 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 36.81 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Granted, Weighted Average Exercise Price (in dollars per share) | $ 98.91 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 70.94 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 65.80 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Exercised, Weighted Average Exercise Price (in dollars per share) | $ 42.07 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 34.51 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 35.65 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember
Canceled or expired, Weighted Average Exercise Price (in dollars per share) | $ 68.89 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 0 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 58.28 us-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) | $ 69.95 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 55.42 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_EmployeePlanMember | $ 45.54 us-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) | 320,322 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 345,938 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 353,625 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Granted, Outstanding Non-Qualified or Nonincentive Stock Awards (in shares) | 42,000 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 54,958 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriod / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 66,306 us-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) | 298,334 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 320,322 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | 345,938 us-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) | $ 50.64 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 45.84 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 39.05 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Granted, Weighted Average Exercise Price (in dollars per share) | $ 99.52 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 75.17 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 62.39 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember
Exercised, Weighted Average Exercise Price (in dollars per share) | $ 39.08 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 46.75 us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 28.22 us-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) | $ 60.01 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 50.64 us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice / us-gaap_AwardTypeAxis = us-gaap_EmployeeStockOptionMember / us-gaap_PlanNameAxis = kex_DirectorPlanMember | $ 45.84 us-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 | $ 16,271,000 us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized / us-gaap_AwardTypeAxis = us-gaap_RestrictedStockMember |  |
Weighted average period of recognition in years | 2 years 7 months 6 days |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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- Definition Unrecognized cost of unvested share-based compensation awards. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of equity-based payment instruments, excluding stock (or unit) options, that were forfeited during the reporting period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Fair value of share-based awards for which the grantee gained the right by satisfying service and performance requirements, to receive or retain shares or units, other instruments, or cash. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The estimated dividend rate (a percentage of the share price) to be paid (expected dividends) to holders of the underlying shares over the option's term. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Expected term of share-based compensation awards, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 14.D.2) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section D -Subsection 2 + Details
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- Definition The estimated measure of the percentage by which a share price is expected to fluctuate during a period. Volatility also may be defined as a probability-weighted measure of the dispersion of returns about the mean. The volatility of a share price is the standard deviation of the continuously compounded rates of return on the share over a specified period. That is the same as the standard deviation of the differences in the natural logarithms of the stock prices plus dividends, if any, over the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The risk-free interest rate assumption that is used in valuing an option on its own shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (f)(2)(iv) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The difference between the maximum number of shares (or other type of equity) authorized for issuance under the plan (including the effects of amendments and adjustments), and the sum of: 1) the number of shares (or other type of equity) already issued upon exercise of options or other equity-based awards under the plan; and 2) shares (or other type of equity) reserved for issuance on granting of outstanding awards, net of cancellations and forfeitures, if applicable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of difference between fair value of the underlying shares reserved for issuance and exercise price of vested portions of options outstanding and currently exercisable. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares into which fully or partially vested stock options outstanding as of the balance sheet date can be currently converted under the option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount of accumulated difference between fair value of underlying shares on dates of exercise and exercise price on options exercised (or share units converted) into shares. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (d)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares under options that were cancelled during the reporting period as a result of occurrence of a terminating event specified in contractual agreements pertaining to the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(3) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Net number of share options (or share units) granted during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(1) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Amount by which the current fair value of the underlying stock exceeds the exercise price of options outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of options outstanding, including both vested and non-vested options. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which grantees can acquire the shares reserved for issuance under the stock option plan. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Weighted average price at which option holders acquired shares when converting their stock options into shares. + References No definition available. + Details
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- Definition Weighted average price at which grantees could have acquired the underlying shares with respect to stock options that were terminated. + References No definition available. + Details
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- Definition Weighted average exercise price as of the balance sheet date for those equity-based payment arrangements exercisable and outstanding. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The floor of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares reserved for issuance pertaining to the outstanding exercisable stock options as of the balance sheet date in the customized range of exercise prices for which the market and performance vesting condition has been satisfied. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(iii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The number of shares reserved for issuance pertaining to the outstanding stock options as of the balance sheet date for all option plans in the customized range of exercise prices. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The weighted average price as of the balance sheet date at which grantees could acquire the underlying shares with respect to all outstanding stock options which are in the customized range of exercise prices. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(i)-(ii) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition The ceiling of a customized range of exercise prices for purposes of disclosing shares potentially issuable under outstanding stock option awards on all stock option plans and other required information pertaining to awards in the customized range. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (g) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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- Definition Number of share options (or share units) exercised during the current period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6928386&loc=d3e21463-112644 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=27012166&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.28,29) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(2) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 29, 30 -Article 5 + Details
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