Securities Available for sale, Unrealized Loss Position, Fair Value (Details) $ in Thousands	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	462	77
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 4,911,358	$ 1,143,562
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	1,476,208	438,846
Available for sale securities, Unrealized Loss Position, Fair Value	6,387,566	1,582,408
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	80,372	8,197
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	33,608	642
Available for sale securities, Unrealized Loss Position, Accumulated Loss	113,980	$ 8,839
Debt Securities, Available-for-sale, Allowance for Credit Loss	$ 0
U.S. Treasury [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 1,000
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	0
Available for sale securities, Unrealized Loss Position, Fair Value	1,000
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	1
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	0
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 1
Municipal securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	175	1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 423,575	$ 6,166
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	22,476	0
Available for sale securities, Unrealized Loss Position, Fair Value	446,051	6,166
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	7,762	5
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	726	0
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 8,488	$ 5
Residential agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	120	38
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 2,382,094	$ 786,890
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	750,044	160,747
Available for sale securities, Unrealized Loss Position, Fair Value	3,132,138	947,637
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	37,121	6,605
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	20,327	120
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 57,448	$ 6,725
Commercial agency mortgage-backed securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	165	37
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 2,104,689	$ 350,506
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	703,216	277,627
Available for sale securities, Unrealized Loss Position, Fair Value	2,807,905	628,133
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	35,488	1,587
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	12,527	494
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 48,015	$ 2,081
Other debt securities [Member]
Available for sale, Unrealized Loss Position [Line Items]
Available for sale, Securities in Unrealized Loss Positions, Qualitative Disclosure, Number of Positions	1	1
Available for sale, Securities in Unrealized Loss Position, Less than 12 Months [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Fair Value	$ 0	$ 0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Fair Value	472	472
Available for sale securities, Unrealized Loss Position, Fair Value	472	472
Available for sale securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]
Available for sale securities, Continuous Unrealized Loss Position, Less than 12 Months, Accumulated Loss	0	0
Available for sale securities, Continuous Unrealized Loss Position, 12 Months or Longer, Accumulated Loss	28	28
Available for sale securities, Unrealized Loss Position, Accumulated Loss	$ 28	$ 28

Available-for-sale Securities, Securities in Unrealized Loss Position, Accumulated Loss [Abstract]

No definition available.

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

- Definition

Available-for-sale, Securities in Unrealized Loss Position, Fair Value [Abstract] [Abstract]

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

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

- Definition

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

+ Details

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

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27337-111563

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLonger
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPosition12MonthsOrLongerAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27337-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922890-210455

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12Months
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for less than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleContinuousUnrealizedLossPositionLessThan12MonthsAccumulatedLoss
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 6
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27290-111563

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 4
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922888-210455

Reference 3: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=121590138&loc=SL82922954-210456

+ Details

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

- Definition

Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

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

- Definition

Number of investments in debt securities measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position, without allowance for credit loss. Includes beneficial interest in securitized financial asset.

+ References

+ Details

Name:	us-gaap_DebtSecuritiesAvailableForSaleUnrealizedLossPositionNumberOfPositions
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USTreasurySecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_USStatesAndPoliticalSubdivisionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_MortgageBackedSecuritiesIssuedByUSGovernmentSponsoredEnterprisesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommercialMortgageBackedSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_OtherDebtSecuritiesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: