XML 21 R50.htm IDEA: XBRL DOCUMENT v2.4.1.9
Mortgage Banking Activities, Loan Servicing Portfolio (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Stratification of Mortgage Loan Servicing Portfolio [Line Items]        
Fair value $ 175,051,000us-gaap_ServicingAssetAtFairValueAmount $ 171,976,000us-gaap_ServicingAssetAtFairValueAmount $ 153,774,000us-gaap_ServicingAssetAtFairValueAmount $ 153,333,000us-gaap_ServicingAssetAtFairValueAmount
Outstanding principal of loans serviced for others 16,937,128,000bokf_LoansServicedForOthers      
Weighted average prepayment rate (in hundredths) 10.53%bokf_WeightedAveragePrepaymentRate      
Economic hedge threshold for interest rate sensitivity for mortgage servicing rights and securities held (in basis points) 50bokf_EconomicHedgeThresholdForInterestRateSensitivityForMortgageServicingRightsAndSecuritiesHeld      
Dollar increase in fair value, net of economic hedge, of mortgage servicing rights due to a 50 basis point increase in mortgage interest rates 2,300,000bokf_IncreaseInFairValueOfMortgageServicingRightsDueTo50BasisPointIncreaseInMortgageInterestRates      
Dollar increase in fair value, net of economic hedge, of mortgage servicing rights due to a 50 basis point decrease in mortgage interest rates 1,400,000bokf_DecreaseInFairValueOfMortgageServicingRightsDueTo50BasisPointDecreaseInMortgageInterestRates      
Interest Rate Range Less than 4.00% [Member]        
Stratification of Mortgage Loan Servicing Portfolio [Line Items]        
Fair value 76,549,000us-gaap_ServicingAssetAtFairValueAmount
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeLessThan400Member
     
Outstanding principal of loans serviced for others 7,280,513,000bokf_LoansServicedForOthers
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeLessThan400Member
     
Weighted average prepayment rate (in hundredths) 7.90%bokf_WeightedAveragePrepaymentRate
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeLessThan400Member
     
Interest Rate Range 4.00% to 4.99% [Member]        
Stratification of Mortgage Loan Servicing Portfolio [Line Items]        
Fair value 77,787,000us-gaap_ServicingAssetAtFairValueAmount
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange400To499Member
     
Outstanding principal of loans serviced for others 6,864,077,000bokf_LoansServicedForOthers
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange400To499Member
     
Weighted average prepayment rate (in hundredths) 8.85%bokf_WeightedAveragePrepaymentRate
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange400To499Member
     
Interest Rate Range 5.00% to 5.99% [Member]        
Stratification of Mortgage Loan Servicing Portfolio [Line Items]        
Fair value 16,586,000us-gaap_ServicingAssetAtFairValueAmount
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange500To599Member
     
Outstanding principal of loans serviced for others 1,881,950,000bokf_LoansServicedForOthers
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange500To599Member
     
Weighted average prepayment rate (in hundredths) 16.40%bokf_WeightedAveragePrepaymentRate
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRange500To599Member
     
Interest Rate Range Greater than 5.99% [Member]        
Stratification of Mortgage Loan Servicing Portfolio [Line Items]        
Fair value 4,129,000us-gaap_ServicingAssetAtFairValueAmount
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeGreaterThan599Member
     
Outstanding principal of loans serviced for others $ 910,588,000bokf_LoansServicedForOthers
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeGreaterThan599Member
     
Weighted average prepayment rate (in hundredths) 32.16%bokf_WeightedAveragePrepaymentRate
/ bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis
= bokf_InterestRateRangeGreaterThan599Member