Name:	bokf_DecreaseIncreaseinFairValueOfMortgageServicingRightsDueTo50BasisPointDecreaseInMortgageInterestRates
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The economic hedge threshold utilized in financial model to estimate interest rate sensitivity in determining fair value of mortgage servicing rights.

No definition available.

Name:	bokf_EconomicHedgeThresholdForInterestRateSensitivityForMortgageServicingRightsAndSecuritiesHeld
Namespace Prefix:	bokf_
Data Type:	xbrli:integerItemType
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Period Type:	instant

The dollar amount of increase (decrease) in the estimated fair value of mortgage servicing rights as a result of a 50 basis point (.5%) increase in prevailing mortgage interest rates.

No definition available.

Name:	bokf_IncreasedecreaseinFairValueOfMortgageServicingRightsDueTo50BasisPointIncreaseInMortgageInterestRates
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

The dollar amount of principal for mortgage loans being serviced for others.

No definition available.

Name:	bokf_LoansServicedForOthers
Namespace Prefix:	bokf_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

-- None. No documentation exists for this element. --

No definition available.

Name:	bokf_StratificationOfMortgageLoanServicingPortfolioLineItems
Namespace Prefix:	bokf_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Annual prepayment estimates based on loan interest rate, original term and loan type as of the balance sheet date.

No definition available.

Name:	bokf_WeightedAveragePrepaymentRate
Namespace Prefix:	bokf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 50
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=56950315&loc=d3e122625-111746

Name:	us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Name:	bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis=bokf_InterestRateRangeLessThan400Member
Namespace Prefix:
Data Type:	na
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Period Type:

Name:	bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis=bokf_InterestRateRange400To499Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	bokf_MortgageLoanServicingPortfolioByInterestRateRangeAxis=bokf_InterestRateRange500To599Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: