Loans and Allowance for Credit Losses, Loans by Portfolio Type (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	$ 6,339,409	$ 6,603,265
Loans, variable rate of interest	14,837,600	13,468,356
Loans, non-accrual	114,139	134,059
Total	21,291,148	20,205,680
Credit Commitments [Abstract]
Outstanding commitments to extend credit	13,500,000
Outstanding standby letters of credit	701,000
Commercial [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	3,410,376	3,360,117
Loans, variable rate of interest	10,113,713	9,072,244
Loans, non-accrual	54,608	74,104
Total	13,578,697	12,506,465
Commercial real estate [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	874,850	929,015
Loans, variable rate of interest	3,220,359	2,888,048
Loans, non-accrual	10,939	14,262
Total	4,106,148	3,831,325
Paycheck Protection Program [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	43,140	276,341
Loans, variable rate of interest	0	0
Loans, non-accrual	0	0
Total	43,140	276,341
Loans to individuals [Member]
Loan receivables disclosure [Abstract]
Loans, fixed rate of interest	2,011,043	2,037,792
Loans, variable rate of interest	1,503,528	1,508,064
Loans, non-accrual	48,592	45,693
Total	$ 3,563,163	$ 3,591,549

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

No definition available.

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- References

No definition available.

+ Details

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

- Definition

Amount before allowance of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Includes deferred interest and fees, undisbursed portion of loan balance, unamortized costs and premiums and discounts from face amounts. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=124259787&loc=d3e4428-111522

+ Details

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

- Definition

Reflects the carrying amount of loans deemed to be questionable as to collection on which no interest is continuing to be recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 7
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=123577603&loc=d3e5111-111524

+ Details

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

- Definition

Amount of loan with fixed rate of interest.

+ References

+ Details

Name:	us-gaap_LoansReceivableWithFixedRatesOfInterest1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of loan with variable or adjustable rate of interest.

+ References

+ Details

Name:	us-gaap_LoansReceivableWithVariableRatesOfInterest1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Unused amount of commitments to extend credit to customers.

+ References

No definition available.

+ Details

Name:	us-gaap_UnusedCommitmentsToExtendCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialPortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_CommercialRealEstatePortfolioSegmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bokf_PaycheckProtectionProgramMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivablePortfolioSegmentAxis=bokf_LoanstoindividualsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: