XML 22 R42.htm IDEA: XBRL DOCUMENT v2.4.1.9
Loans and Allowances for Credit Losses, Credit Quality Indicators (Details) (USD $)
In Thousands, unless otherwise specified
Mar. 31, 2015
Dec. 31, 2014
Mar. 31, 2014
Dec. 31, 2013
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment $ 12,840,895bokf_InternallyRiskGradedRecordedInvestment $ 12,336,710bokf_InternallyRiskGradedRecordedInvestment $ 11,140,443bokf_InternallyRiskGradedRecordedInvestment  
Non-Graded, Recorded Investment 1,843,241bokf_NonGradedRecordedInvestment 1,871,327bokf_NonGradedRecordedInvestment 1,937,411bokf_NonGradedRecordedInvestment  
Total 14,684,136us-gaap_LoansAndLeasesReceivableGrossCarryingAmount 14,208,037us-gaap_LoansAndLeasesReceivableGrossCarryingAmount 13,077,854us-gaap_LoansAndLeasesReceivableGrossCarryingAmount  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 145,825bokf_InternallyRiskGradedAllowance 137,032bokf_InternallyRiskGradedAllowance 133,382bokf_InternallyRiskGradedAllowance  
Non-Graded, Related Allowance 23,788bokf_NonGradedAllowance 23,979bokf_NonGradedAllowance 27,971bokf_NonGradedAllowance  
Total, Related Allowance 197,686us-gaap_LoansAndLeasesReceivableAllowance 189,056us-gaap_LoansAndLeasesReceivableAllowance 188,318us-gaap_LoansAndLeasesReceivableAllowance 185,396us-gaap_LoansAndLeasesReceivableAllowance
Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 12,687,045bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 12,222,486bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 11,001,684bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 1,798,601bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,825,709bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,897,379bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 117,757bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 79,071bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 74,085bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 36,093bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 35,153bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 64,674bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 44,640bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 45,618bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 40,032bokf_NonGradedRecordedInvestment
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Commercial [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 9,367,119bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 9,073,030bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 8,029,443bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Non-Graded, Recorded Investment 24,044bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 22,640bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 22,263bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Total 9,391,163us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 9,095,670us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 8,051,706us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 100,592bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 90,085bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 84,333bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Non-Graded, Related Allowance 819bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 790bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 913bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Total, Related Allowance 101,411us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 90,875us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		 85,246us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember		  
Commercial [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 9,252,509bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 9,008,360bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 7,972,912bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 23,957bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 22,532bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 22,149bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Commercial [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 100,817bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 51,251bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 37,598bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Commercial [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 13,793bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 13,419bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 18,933bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 87bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 108bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 114bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Energy [Member]        
Recorded Investment [Abstract]        
Total 2,902,994us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember		 2,860,428us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember		 2,344,072us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember		  
Energy [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,857,004bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,843,093bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,339,578bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Energy [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 44,115bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 15,919bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,735bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Energy [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 1,875bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 1,416bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 1,759bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_EnergyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Services [Member]        
Recorded Investment [Abstract]        
Total 2,728,354us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember		 2,518,229us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember		 2,232,471us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember		  
Services [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,709,357bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,497,888bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,213,569bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Services [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 14,253bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 15,140bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 14,321bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Services [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 4,744bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 5,201bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 4,581bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ServicesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Wholesale/retail [Member]        
Recorded Investment [Abstract]        
Total 1,270,322us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember		 1,313,316us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember		 1,225,990us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember		  
Wholesale/retail [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 1,241,961bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,301,026bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,216,725bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Wholesale/retail [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 23,960bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 8,141bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,411bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Wholesale/retail [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 4,401bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 4,149bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 6,854bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_WholesaleAndRetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Manufacturing [Member]        
Recorded Investment [Abstract]        
Total 560,925us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember		 532,594us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember		 444,215us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember		  
Manufacturing [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 546,566bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 527,951bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 429,523bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Manufacturing [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 13,942bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 4,193bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 11,127bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Manufacturing [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 417bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 450bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,565bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_ManufacturingMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Healthcare [Member]        
Recorded Investment [Abstract]        
Total 1,511,177us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember		 1,454,969us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember		 1,396,562us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember		  
Healthcare [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 1,505,072bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,449,024bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,392,315bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Healthcare [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 4,547bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 4,565bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,804bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Healthcare [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 1,558bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 1,380bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 1,443bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_HealthcareMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Other commercial and industrial [Member]        
Recorded Investment [Abstract]        
Total 417,391us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember		 416,134us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember		 408,396us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember		  
Other commercial and industrial [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 392,549bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 389,378bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 381,202bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 23,957bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 22,532bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 22,149bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Other commercial and industrial [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 3,293bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 4,200bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Other commercial and industrial [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 798bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 823bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 731bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 87bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 108bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 114bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialAndIndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Commercial Real Estate [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,935,464bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 2,728,150bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 2,631,407bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Total 2,935,464us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 2,728,150us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 2,631,407us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 40,819bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 42,445bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 41,589bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Non-Graded, Related Allowance 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Total, Related Allowance 40,819us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 42,445us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		 41,589us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember		  
Commercial Real Estate [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,900,708bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,683,565bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 2,558,346bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Commercial Real Estate [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 14,854bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 26,028bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 33,756bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Commercial Real Estate [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 19,902bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 18,557bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 39,305bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Residential construction and land development [Member]        
Recorded Investment [Abstract]        
Total 139,152us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember		 143,591us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember		 184,820us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember		  
Residential construction and land development [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 128,795bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 127,437bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 153,836bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Residential construction and land development [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 759bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 10,855bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 14,437bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Residential construction and land development [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 9,598bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 5,299bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 16,547bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_CommercialRealEstateConstructionFinancingReceivableMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Retail [Member]        
Recorded Investment [Abstract]        
Total 658,860us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember		 666,889us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember		 640,506us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember		  
Retail [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 654,429bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 662,335bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 634,253bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Retail [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 574bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 628bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 1,627bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Retail [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 3,857bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,926bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 4,626bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_RetailMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Office [Member]        
Recorded Investment [Abstract]        
Total 513,862us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember		 415,544us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember		 436,264us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember		  
Office [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 510,881bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 411,548bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 428,815bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Office [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 571bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 576bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 1,148bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Office [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,410bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,420bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 6,301bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OfficeMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Multifamily [Member]        
Recorded Investment [Abstract]        
Total 749,986us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember		 704,298us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember		 662,674us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember		  
Multifamily [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 737,750bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 691,053bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 648,999bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Multifamily [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 12,236bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 13,245bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 13,675bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Multifamily [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_MultifamilyMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Industrial [Member]        
Recorded Investment [Abstract]        
Total 478,584us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember		 428,817us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember		 305,207us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember		  
Industrial [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 478,508bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 428,817bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 304,321bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Industrial [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Industrial [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 76bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 886bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_IndustrialMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Other commercial real estate [Member]        
Recorded Investment [Abstract]        
Total 395,020us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember		 369,011us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember		 401,936us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember		  
Other commercial real estate [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 390,345bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 362,375bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 388,122bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Other commercial real estate [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 714bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 724bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,869bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Other commercial real estate [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 3,961bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 5,912bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 10,945bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_OtherCommercialRealEstateMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Residential Mortgage [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 196,782bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 192,303bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 209,608bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Non-Graded, Recorded Investment 1,730,217bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 1,757,209bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 1,809,067bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Total 1,926,999us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 1,949,512us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 2,018,675us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 3,028bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 2,996bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 4,695bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Non-Graded, Related Allowance 20,216bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 20,462bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 23,612bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Total, Related Allowance 23,244us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 23,458us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		 28,307us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember		  
Residential Mortgage [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 192,473bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 187,520bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 200,662bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 1,685,970bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,712,098bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 1,769,929bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Residential Mortgage [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,069bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 1,773bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,704bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Residential Mortgage [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,240bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,010bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 6,242bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 44,247bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 45,111bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 39,138bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Permanent mortage [Member]        
Recorded Investment [Abstract]        
Total 964,264us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember		 969,951us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember		 1,033,572us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember		  
Permanent mortage [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 192,473bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 187,520bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 200,662bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 736,357bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 745,813bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 793,864bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Permanent mortage [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,069bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 1,773bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 2,704bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Permanent mortage [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 2,240bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,010bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 6,242bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 31,125bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 31,835bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 30,100bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentResidentialMortgageMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Permanent mortgages guaranteed by US govenment agencies [Member]        
Recorded Investment [Abstract]        
Total 200,179us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember		 205,950us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember		 184,822us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember		  
Permanent mortgages guaranteed by US govenment agencies [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 196,923bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 202,238bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 183,250bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Permanent mortgages guaranteed by US govenment agencies [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Permanent mortgages guaranteed by US govenment agencies [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 3,256bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 3,712bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 1,572bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Home equity {Member]        
Recorded Investment [Abstract]        
Total 762,556us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember		 773,611us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember		 800,281us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember		  
Home equity {Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 752,690bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 764,047bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 792,815bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Home equity {Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Home equity {Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 9,866bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 9,564bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 7,466bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_HomeEquityMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Consumer [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 341,530bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 343,227bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 269,985bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Non-Graded, Recorded Investment 88,980bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 91,478bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 106,081bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Total 430,510us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 434,705us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 376,066us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 1,386bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 1,506bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 2,765bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Non-Graded, Related Allowance 2,753bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 2,727bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 3,446bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Total, Related Allowance 4,139us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 4,233us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		 6,211us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember		  
Consumer [Member] | Performing [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 341,355bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 343,041bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 269,764bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Non-Graded, Recorded Investment 88,674bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 91,079bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		 105,301bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= us-gaap_PerformingFinancingReceivableMember		  
Consumer [Member] | Potential Problem [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 17bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 19bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		 27bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_PotentialProblemFinancingReceivableMember		  
Consumer [Member] | Nonaccrual [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 158bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 167bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 194bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Non-Graded, Recorded Investment 306bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 399bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		 780bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_ConsumerLoanMember
/ us-gaap_InternalCreditAssessmentAxis
= bokf_NonaccrualFinancingReceivableMember		  
Specific Allowance [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 12,840,895bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 12,336,710bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 11,140,443bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Non-Graded, Recorded Investment 1,843,241bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 1,871,327bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 1,937,411bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Total 14,684,136us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 14,208,037us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 13,077,854us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 145,825bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 137,032bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 133,382bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Non-Graded, Related Allowance 23,788bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 23,979bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 27,971bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Total, Related Allowance 169,613us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 161,011us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		 161,353us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= bokf_SpecificAllowanceMember		  
Nonspecific Allowance [Member]        
Recorded Investment [Abstract]        
Internally Risk Graded, Recorded Investment 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_InternallyRiskGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		  
Non-Graded, Recorded Investment 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_NonGradedRecordedInvestment
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		  
Total 0us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0us-gaap_LoansAndLeasesReceivableGrossCarryingAmount
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		  
Related Allowance [Abstract]        
Internally Risk Graded, Related Allowance 0bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_InternallyRiskGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		  
Non-Graded, Related Allowance 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 0bokf_NonGradedAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		  
Total, Related Allowance $ 28,073us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 $ 28,045us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 $ 26,965us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember		 $ 28,213us-gaap_LoansAndLeasesReceivableAllowance
/ us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis
= us-gaap_UnallocatedFinancingReceivablesMember