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

Represents fair value of other real estate owned as a percentgage of appraised value, high end of range

No definition available.

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

Represents fair value of other real estate owned as a percentgage of appraised value, low end of range

No definition available.

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

Represents fair value of other real estate owned as a percentgage of appraised value, weighted average

No definition available.

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

Fair Value of Impaired Loans as a Percentage of Unpaid Principal Balance [Abstract]

No definition available.

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

Represents the highest percentage in the range of fair values of impaired loans to the unpaid principal balance.

No definition available.

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

Represents the lowest percentage in the range of fair values of impaired loans to the unpaid principal balance.

No definition available.

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

Represents the weighted average of the fair values of impaired loans to the unpaid principal balance at the balance sheet date.

No definition available.

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

Fair Value of Real Estate and Other Repossessed Assets as a Percentage of Appraised Value [Abstract]

No definition available.

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

This element represents the aggregate of the assets reported on the balance sheet at period end measured at fair value on a nonrecurring basis by the entity. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

No definition available.

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

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Description of significant assumptions used by management to measure fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 10
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13433-108611

Name:	us-gaap_FairValueMeasurementsSignificantAssumptions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Description of the inputs and valuation technique(s) used to measure fair value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

Name:	us-gaap_FairValueMeasurementsValuationTechniques
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsNonrecurringMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByAssetClassAxis=bokf_FairValueImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: