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Share-Based Compensation Plans (Details) (USD $)
12 Months Ended 1 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jan. 31, 2015
May 31, 2014
Dec. 31, 2011
Share-based Compensation, Deferred Compensation Plans, 2011 True-Up Plan [Abstract]            
Additional Compensation Accrued for Certain Senior Executive Related to 2011 True-Up Plan   $ 69,000,000bokf_AdditionalCompensationAccruedForCertainSeniorExecutiveRelatedTo2011TrueUpPlan        
Total Amount Distributed Under 2011 True-Up Plan         56,000,000bokf_TotalAmountDistributedUnder2011TrueUpPlan  
Cash Distributed Related to 2011 True-Up Plan         35,000,000bokf_CashDistributedRelatedto2011TrueUpPlan  
Dollar Value of Shares Distributed Related to 2011 True-Up Plan         21,000,000bokf_DollarValueofSharesDistributedRelatedto2011TrueUpPlan  
Number of Shares Distributed Related to 2011 True-Up Plan         331,000bokf_NumberofSharesDistributedRelatedto2011TrueUpPlan  
Price Per Share of Shares Distributed Related to 2011 True-Up Plan         $ 64.91bokf_PricePerShareofSharesDistributedRelatedto2011TrueUpPlan  
Stock Options [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Beginning balance (in shares) 1,135,105us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,890,786us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2,621,347us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options awarded (in shares) 0us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
81,492us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
67,155us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options exercised (in shares) (323,004)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(608,663)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(708,295)us-gaap_StockIssuedDuringPeriodSharesStockOptionsExercised
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options forfeited (in shares) (15,509)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(219,342)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(22,559)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options expired (in shares) (2,701)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(9,168)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
(66,862)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExpirationsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Number of options outstanding, Ending balance (in shares) 793,891us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,135,105us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,890,786us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options shares vested (in shares) 347,633us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
424,459us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
601,367us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, beginning balance (in dollars per share) $ 49.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 48.29us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 47.01us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options awarded, weighted average exercise price (in dollars per share) $ 0.00us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 55.74us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 58.76us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options exercised, weighted average exercise price (in dollars per share) $ 49.17us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 48.00us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 45.32us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExercisesInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options forfeited, weighted average exercise price (in dollars per share) $ 45.71us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 47.65us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 50.36us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsForfeituresInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options expired, weighted average exercise price (in dollars per share) $ 47.98us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 50.61us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 45.97us-gaap_ShareBasedCompensationArrangementsByShareBasedPaymentAwardOptionsExpirationsInPeriodWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 49.05us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 49.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 48.29us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options vested, weighted average exercise price (in dollars per share) $ 48.85us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 49.49us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 47.99us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Options outstanding, aggregate intrinsic value 8,725,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
19,564,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
11,748,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
    20,769,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
Options vested, aggregate intrinsic value 3,889,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
7,146,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
3,890,000us-gaap_SharebasedCompensationArrangementBySharebasedPaymentAwardOptionsExercisableIntrinsicValue1
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Options exercised, aggregate intrinsic value 5,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
8,500,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
8,300,000us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsExercisesInPeriodTotalIntrinsicValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Weighted average assumptions used to determine fair value of stock options awarded [Abstract]            
Average risk-free interest rate (in hundredths)   0.89%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
[1] 0.93%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsRiskFreeInterestRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
[1]      
Dividend yield (in hundredths)   2.80%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
2.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedDividendRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Volatility factors   27.20%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
28.00%us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardFairValueAssumptionsExpectedVolatilityRate
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Weighted average expected life (in years)   4 years 10 months 24 days 4 years 10 months 24 days      
Weighted average fair value (in dollars per share)   $ 9.67us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
$ 11.48us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Share-based Compensation Expense Recognized 826,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
1,300,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
4,100,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
     
Share-based Compensation Costs, Including Costs That May Be Recognized As Future Expense [Abstract]            
Unrecognized compensation cost of unvested awards, for future periods 980,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2015 475,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinNextTwelveMonths
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2016 275,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearTwo
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2017 152,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearThree
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2018 60,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearFour
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Unrecognized compensation cost of unvested awards, Amount to be Expensed in 2019 18,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearFive
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
         
Share-based Compensation, Deferred Compensation Plans, 2011 True-Up Plan [Abstract]            
Vesting period (in years) 7 years          
Stock Options [Member] | Exercise Price 36.65 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 190,832us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice3665Member
         
Options shares vested (in shares) 65,626us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice3665Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 6 months 5 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 36.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice3665Member
         
Options vested, weighted average exercise price (in dollars per share) $ 36.65us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice3665Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 2 years 10 months          
Stock Options [Member] | Exercise Price 45.15 - 47.34 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 33,574us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice45154734Member
         
Options shares vested (in shares) 33,574us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice45154734Member
         
Weighted average remaining contractual life of options vested (in years) 9 months 2 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 47.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice45154734Member
         
Options vested, weighted average exercise price (in dollars per share) $ 47.09us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice45154734Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 9 months 2 days          
Stock Options [Member] | Exercise Price 48.30 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 39,557us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4830Member
         
Options shares vested (in shares) 13,326us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4830Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 5 months          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 48.30us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4830Member
         
Options vested, weighted average exercise price (in dollars per share) $ 48.30us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4830Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 3 years 1 month 27 days          
Stock Options [Member] | Exercise Price 48.46 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 169,422us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4846Member
         
Options shares vested (in shares) 95,415us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4846Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 5 months 25 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 48.46us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4846Member
         
Options vested, weighted average exercise price (in dollars per share) $ 48.46us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice4846Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 2 years 1 month 27 days          
Stock Options [Member] | Exercise Price 54.33 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 78,904us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5433Member
         
Options shares vested (in shares) 78,904us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5433Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 5 months 22 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 54.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5433Member
         
Options vested, weighted average exercise price (in dollars per share) $ 54.33us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5433Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 1 year 5 months 22 days          
Stock Options [Member] | Exercise Price 55.74 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 78,108us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.74Member
         
Options shares vested (in shares) 8,260us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.74Member
         
Weighted average remaining contractual life of options vested (in years) 2 years 10 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 55.74us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.74Member
         
Options vested, weighted average exercise price (in dollars per share) $ 55.74us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.74Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 5 years 1 month 27 days          
Stock Options [Member] | Exercise Price 55.94 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 125,285us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.94Member
         
Options shares vested (in shares) 37,008us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.94Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 5 months 8 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 55.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.94Member
         
Options vested, weighted average exercise price (in dollars per share) $ 55.94us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice55.94Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 3 years 7 months 12 days          
Stock Options [Member] | Exercise Price 58.76 [Member]            
Share-based Compensation Arrangements by Share-based Payment Award, Options, Outstanding, Number of Options [Abstract]            
Number of options outstanding, Ending balance (in shares) 78,209us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5876Member
         
Options shares vested (in shares) 15,520us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingNumber
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5876Member
         
Weighted average remaining contractual life of options vested (in years) 1 year 7 months 2 days          
Share-based Compensation Arrangements by Share-based Payment Award, Options, Weighted Average Exercise Price [Abstract]            
Options outstanding, weighted average exercise price, ending balance (in dollars per share) $ 58.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5876Member
         
Options vested, weighted average exercise price (in dollars per share) $ 58.76us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsVestedAndExpectedToVestOutstandingWeightedAverageExercisePrice
/ us-gaap_AwardTypeAxis
= us-gaap_EmployeeStockOptionMember
/ us-gaap_ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansByExercisePriceRangeAxis
= bokf_ExercisePrice5876Member
         
Share-based Compensation Arrangements by Share-based Payment Award, Options, Intrinsic Value [Abstract]            
Weighted average remaining contractual life (in years) 4 years 4 months 5 days          
Non-vested Common Stock [Member]            
Weighted average assumptions used to determine fair value of stock options awarded [Abstract]            
Share-based Compensation Expense Recognized 10,000,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
6,900,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
5,600,000us-gaap_AllocatedShareBasedCompensationExpense
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Share-based Compensation Costs, Including Costs That May Be Recognized As Future Expense [Abstract]            
Unrecognized compensation cost of unvested awards, for future periods 15,500,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2015 9,300,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinNextTwelveMonths
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2016 5,700,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearTwo
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2017 474,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearThree
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Unrecognized compensation cost of unvested awards, Amount to be expensed in 2018 1,000bokf_EmployeeServiceSharebasedCompensationNonvestedAwardsCompensationCostsNotYetRecognizedAmounttobeExpensedinYearFour
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
         
Share-based Compensation Arrangements by Share-based Payment Award, Restricted Stock, Nonvested, Number of Shares [Roll Forward]            
Non-vested common shares awarded, beginning of period (in shares) 647,989us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
592,831us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
503,738us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Non-vested common shares awarded during period (in shares) 206,621us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
211,791us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
197,058us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardNonOptionEquityInstrumentsGranted
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Non-vested shares that vested during period (in shares) (140,820)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
(66,648)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
(76,192)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Non-vested shares that forfeited during period (in shares) (25,179)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
(89,985)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
(31,773)us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeitedInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Non-vested common shares awarded, end of period (in shares) 688,611us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
647,989us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
592,831us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedNumber
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Roll Forward]            
Weighted Average Grant Date Fair Value, Granted $ 64.96us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 55.84us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 55.63us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Weighted Average Grant Date Fair Value, Vested $ 44.56us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 35.93us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 47.32us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsVestedInPeriodWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
Weighted average grant date fair value non-vested stock awards forfeited (in dollars per share) $ 56.26us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 49.95us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
$ 50.45us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsForfeituresWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
     
2015 Restricted Common Stock Award [Member] | Non-vested Common Stock [Member]            
Share-based Compensation Costs, Including Costs That May Be Recognized As Future Expense [Abstract]            
Unrecognized compensation cost of unvested awards, for future periods       $ 16,500,000us-gaap_EmployeeServiceShareBasedCompensationNonvestedAwardsTotalCompensationCostNotYetRecognized
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_SubsequentEventTypeAxis
= bokf_A2015RestrictedCommonStockAwardMember
   
Share-based Compensation, Deferred Compensation Plans, 2011 True-Up Plan [Abstract]            
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period       297,106us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_SubsequentEventTypeAxis
= bokf_A2015RestrictedCommonStockAwardMember
   
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value       $ 55.53us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsNonvestedWeightedAverageGrantDateFairValue
/ us-gaap_AwardTypeAxis
= us-gaap_RestrictedStockMember
/ us-gaap_SubsequentEventTypeAxis
= bokf_A2015RestrictedCommonStockAwardMember
   
Vesting period (in years)       3 years    
Share Based Compensation Arrangement By Share Based Payment Award Award Retention of Shares Period       2 years    
[1] Average risk-free interest rate represents U.S. Treasury rates matched to the expected life of the options.