XML 45 R35.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Significant Accounting Policies Newly Adopted and Pending Accounting Pronouncements (Details) $ in Millions | 6 Months Ended
--- | ---
Jun. 30, 2018 USD ($)
Organization, Consolidation and Presentation of Financial Statements [Abstract] |
Increase of reported right of use assets and liabilities, minimum | $ 100
Increase of reported right of use assets and liabilities maximum | $ 150

X
- Definition Increase of reported right of use assets and liabilities minimum + References No definition available. + Details
Name: | bokf_Increaseofreportedrightofuseassetsandliabilities
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Increase of reported right of use assets and liabilities maximum + References No definition available. + Details
Name: | bokf_Increaseofreportedrightofuseassetsandliabilitiesmaximum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

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