XML 23 R30.htm IDEA: XBRL DOCUMENT
v3.20.1

Significant Accounting Policies Loans and Allowance for Credit Losses (Details) | 3 Months Ended
--- | ---
Mar. 31, 2020
Loans and Allowance for Credit Losses [Abstract] |
Loans, Number of Days Past Due for a Non-Risk Graded Loan to be Placed on Nonaccruing Status | 90 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Placed on Nonaccruing Status | 60 days
Loans and Allowances for Credit Losses, Minimum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off | 60 days
Loans and Allowances for Credit Losses, Maximum No of Days After Which Past Due Non-Risk Graded Loans Are Charged Off | 180 days
Loans, Number of Days After Notification of Chapter 7 Bankruptcy Non-Risk Graded Loan is Charged Off | 60 days

X
- Definition Loans and Allowance for Credit Losses [Abstract] + References No definition available. + Details
Name: | bokf_LoansAndAllowanceForCreditLossesAbstract
Namespace Prefix: | bokf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of days after notification of Chapter 7 bankruptcy for a non-risk graded loan to be charged off + References No definition available. + Details
Name: | bokf_LoansNumberOfDaysAfterNotificationOfChapter7BankruptcyNonRiskGradedLoanIsChargedOff
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The number of days following notification of a borrowers Chapter 7 bankruptcy that a non-risk graded loan is placed on nonaccruing status. + References No definition available. + Details
Name: | bokf_LoansNumberOfDaysAfterNotificationOfChapter7BankruptcyNonRiskGradedLoanIsPlacedOnNonaccruingStatus
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the number of days past due a non-risk graded loan has to be in order to be placed on nonaccruing status. + References No definition available. + Details
Name: | bokf_LoansNumberOfDaysPastDueForNonRiskGradedLoanToBePlacedOnNonaccruingStatus
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Maximum number of days after which past due non-risk graded loans are charged off + References No definition available. + Details
Name: | bokf_MaxNoOfDaysAfterWhichPastDueNonRiskGradedLoansAreChargedOff
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Minimum number of days after which past due non-risk graded loans are charged off + References No definition available. + Details
Name: | bokf_MinimumNoOfDaysAfterWhichPastDueNonRiskGradedLoansAreChargedOff
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration