XML 68 R43.htm IDEA: XBRL DOCUMENT
v3.19.3

Loans and Allowance for Credit Losses, Impaired Loans (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2019 | Dec. 31, 2018
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | $ 446,335 |  | $ 446,335 |  | $ 423,787 |
Impaired loans, recorded investment, total |  | 357,898 |  | 357,898 |  | 346,981 |
Impaired loans, recorded investment with no related allowance |  | 331,468 |  | 331,468 |  | 311,526 |
Impaired loans, recorded investment with related allowance |  | 26,430 |  | 26,430 |  | 35,455 |
Impaired loans, related allowance |  | 7,533 |  | 7,533 |  | 8,732 |
Impaired loans, average recorded investment |  | 367,895 |  | 349,646 |  |  |
Impaired loans, interest income recognized |  | 2,300 |  | 6,757 |  |  |
Commercial [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 186,205 |  | 186,205 |  | 156,163 |
Impaired loans, recorded investment, total |  | 111,706 |  | 111,706 |  | 99,841 |
Impaired loans, recorded investment with no related allowance |  | 85,276 |  | 85,276 |  | 64,386 |
Impaired loans, recorded investment with related allowance |  | 26,430 |  | 26,430 |  | 35,455 |
Impaired loans, related allowance |  | 7,533 |  | 7,533 |  | 8,732 |
Impaired loans, average recorded investment |  | 117,551 |  | 99,544 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Energy [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 139,897 |  | 139,897 |  | 79,675 |
Impaired loans, recorded investment, total |  | 88,894 |  | 88,894 |  | 47,494 |
Impaired loans, recorded investment with no related allowance |  | 62,981 |  | 62,981 |  | 18,639 |
Impaired loans, recorded investment with related allowance |  | 25,913 |  | 25,913 |  | 28,855 |
Impaired loans, related allowance |  | 7,176 |  | 7,176 |  | 5,362 |
Impaired loans, average recorded investment |  | 80,263 |  | 67,705 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Services [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 9,390 |  | 9,390 |  | 13,437 |
Impaired loans, recorded investment, total |  | 6,119 |  | 6,119 |  | 8,567 |
Impaired loans, recorded investment with no related allowance |  | 6,093 |  | 6,093 |  | 8,489 |
Impaired loans, recorded investment with related allowance |  | 26 |  | 26 |  | 78 |
Impaired loans, related allowance |  | 26 |  | 26 |  | 74 |
Impaired loans, average recorded investment |  | 8,103 |  | 5,172 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Wholesale/retail [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 1,718 |  | 1,718 |  | 1,722 |
Impaired loans, recorded investment, total |  | 1,504 |  | 1,504 |  | 1,316 |
Impaired loans, recorded investment with no related allowance |  | 1,243 |  | 1,243 |  | 1,015 |
Impaired loans, recorded investment with related allowance |  | 261 |  | 261 |  | 301 |
Impaired loans, related allowance |  | 101 |  | 101 |  | 101 |
Impaired loans, average recorded investment |  | 1,447 |  | 1,087 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Manufacturing [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 9,153 | [1] | 9,153 | [1] | 10,055 |
Impaired loans, recorded investment, total |  | 8,741 | [1] | 8,741 | [1] | 8,919 |
Impaired loans, recorded investment with no related allowance |  | 8,511 | [1] | 8,511 | [1] | 8,673 |
Impaired loans, recorded investment with related allowance |  | 230 | [1] | 230 | [1] | 246 |
Impaired loans, related allowance |  | 230 | [1] | 230 | [1] | 246 |
Impaired loans, average recorded investment | [1] | 8,677 |  | 8,448 |  |  |
Impaired loans, interest income recognized | [1] | 0 |  | 0 |  |  |
Impaired loans, unpaid principal balance to affiliates |  | 4,700 |  | 4,700 |  |  |
Commercial [Member] | Healthcare [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 17,786 |  | 17,786 |  | 24,319 |
Impaired loans, recorded investment, total |  | 5,978 |  | 5,978 |  | 16,538 |
Impaired loans, recorded investment with no related allowance |  | 5,978 |  | 5,978 |  | 10,563 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 5,975 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 2,949 |
Impaired loans, average recorded investment |  | 11,063 |  | 8,547 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Public finance [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment, total |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with no related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  |  |  | 0 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial [Member] | Other commercial and industrial [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 8,261 |  | 8,261 |  | 26,955 |
Impaired loans, recorded investment, total |  | 470 |  | 470 |  | 17,007 |
Impaired loans, recorded investment with no related allowance |  | 470 |  | 470 |  | 17,007 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 7,998 |  | 8,585 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 24,685 |  | 24,685 |  | 30,138 |
Impaired loans, recorded investment, total |  | 23,185 |  | 23,185 |  | 21,621 |
Impaired loans, recorded investment with no related allowance |  | 23,185 |  | 23,185 |  | 21,621 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 22,427 |  | 22,403 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Residential construction and land development [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 1,306 |  | 1,306 |  | 1,306 |
Impaired loans, recorded investment, total |  | 350 |  | 350 |  | 350 |
Impaired loans, recorded investment with no related allowance |  | 350 |  | 350 |  | 350 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 350 |  | 350 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Retail [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 20,516 |  | 20,516 |  | 27,680 |
Impaired loans, recorded investment, total |  | 20,132 |  | 20,132 |  | 20,279 |
Impaired loans, recorded investment with no related allowance |  | 20,132 |  | 20,132 |  | 20,279 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 20,094 |  | 20,206 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Office [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 855 |  | 855 |  | 0 |
Impaired loans, recorded investment, total |  | 855 |  | 855 |  | 0 |
Impaired loans, recorded investment with no related allowance |  | 855 |  | 855 |  | 0 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 855 |  | 427 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Multifamily [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 286 |  | 286 |  | 301 |
Impaired loans, recorded investment, total |  | 286 |  | 286 |  | 301 |
Impaired loans, recorded investment with no related allowance |  | 286 |  | 286 |  | 301 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 281 |  | 294 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Industrial [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 909 |  | 909 |  | 0 |
Impaired loans, recorded investment, total |  | 909 |  | 909 |  | 0 |
Impaired loans, recorded investment with no related allowance |  | 909 |  | 909 |  | 0 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 454 |  | 454 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Commercial real estate [Member] | Other commercial real estate [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 813 |  | 813 |  | 851 |
Impaired loans, recorded investment, total |  | 653 |  | 653 |  | 691 |
Impaired loans, recorded investment with no related allowance |  | 653 |  | 653 |  | 691 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 393 |  | 672 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Residential mortgage [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 235,107 |  | 235,107 |  | 237,208 |
Impaired loans, recorded investment, total |  | 222,736 |  | 222,736 |  | 225,289 |
Impaired loans, recorded investment with no related allowance |  | 222,736 |  | 222,736 |  | 225,289 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 227,663 |  | 227,448 |  |  |
Impaired loans, interest income recognized |  | 2,300 |  | 6,757 |  |  |
Residential mortgage [Member] | Permanent mortgage [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 24,639 |  | 24,639 |  | 28,716 |
Impaired loans, recorded investment, total |  | 20,165 |  | 20,165 |  | 23,951 |
Impaired loans, recorded investment with no related allowance |  | 20,165 |  | 20,165 |  | 23,951 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 20,984 |  | 22,058 |  |  |
Impaired loans, interest income recognized |  | 280 |  | 894 |  |  |
Residential mortgage [Member] | Permanent mortgages guaranteed by US government agencies [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 197,847 | [2] | 197,847 | [2] | 196,296 | [3]
Impaired loans, recorded investment, total |  | 191,764 | [2] | 191,764 | [2] | 190,866 | [3]
Impaired loans, recorded investment with no related allowance |  | 191,764 | [2] | 191,764 | [2] | 190,866 | [3]
Impaired loans, recorded investment with related allowance |  | 0 | [2] | 0 | [2] | 0 | [3]
Impaired loans, related allowance |  | 0 | [2] | 0 | [2] | 0 | [3]
Impaired loans, average recorded investment | [2] | 196,310 |  | 194,751 |  |  |
Impaired loans, interest income recognized | [2] | 2,020 |  | 5,863 |  |  |
Residential mortgage [Member] | Home equity [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 12,621 |  | 12,621 |  | 12,196 |
Impaired loans, recorded investment, total |  | 10,807 |  | 10,807 |  | 10,472 |
Impaired loans, recorded investment with no related allowance |  | 10,807 |  | 10,807 |  | 10,472 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, average recorded investment |  | 10,369 |  | 10,639 |  |  |
Impaired loans, interest income recognized |  | 0 |  | 0 |  |  |
Personal [Member] |  |  |  |  |  |  |
Impaired loans [Abstract] |  |  |  |  |  |  |
Impaired loans, unpaid principal balance |  | 338 |  | 338 |  | 278 |
Impaired loans, recorded investment, total |  | 271 |  | 271 |  | 230 |
Impaired loans, recorded investment with no related allowance |  | 271 |  | 271 |  | 230 |
Impaired loans, recorded investment with related allowance |  | 0 |  | 0 |  | 0 |
Impaired loans, related allowance |  | 0 |  | 0 |  | $ 0 |
Impaired loans, average recorded investment |  | 254 |  | 251 |  |  |
Impaired loans, interest income recognized |  | $ 0 |  | $ 0 |  |  |
[1] | Impaired manufacturing sector loans included $4.7 million of loans from an affiliated entity, with no allowance as the fair value of the collateral exceeded the outstanding principal balance at September 30, 2019.
[2] | All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At September 30, 2019, the majority were accruing based on the guarantee by U.S. government agencies.
[3] | All permanent mortgage loans guaranteed by U.S. government agencies are considered impaired as we do not expect full collection of contractual principal and interest. At December 31, 2018, the majority were accruing based on the guarantee by U.S. government agencies.

X
- Definition Impaired Affiliated Loans + References No definition available. + Details
Name: | bokf_ImpairedAffiliatedLoans
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(1) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 17 -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5258-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableAverageRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (c)(2) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of allowance for credit losses related to recorded investment. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(3) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableRelatedAllowance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 15 -Subparagraph (a)(4) -URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableUnpaidPrincipalBalance
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in impaired financing receivables for which there is no related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithNoRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount of investment in impaired financing receivables for which there is a related allowance for credit losses. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 14A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953550-111524 + Details
Name: | us-gaap_ImpairedFinancingReceivableWithRelatedAllowanceRecordedInvestment
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LoanAndLeaseReceivablesImpairedAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_EnergyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_ServicesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_WholesaleAndRetailMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_ManufacturingMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HealthCareMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_PublicFinanceMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_OtherCommercialAndIndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_ResidentialconstructionandlanddevelopmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_RetailMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_OfficeMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=srt_MultifamilyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_IndustrialMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_OtherCommercialRealEstateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ResidentialPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_PermanentResidentialMortgageMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=bokf_PermanentMortgagesGuaranteedByUsGovernmentAgenciesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=us-gaap_HomeEquityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FinancingReceivablePortfolioSegmentAxis=us-gaap_ConsumerPortfolioSegmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |