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v3.20.4

Significant Accounting Policies Cash Equivalents (Details) | 12 Months Ended
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Dec. 31, 2020
Cash and Cash Equivalents [Abstract] |
Maturity of Federal Funds Sold Considered Cash Equivalents | one day
Maturity of Resell Agreement Considered Cash Equivalents, Minimum | one day
Maturity of Resell Agreements Considered Cash Equivalents, Maximum | 30 days

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- Definition Maturity of Federal Funds Sold Considered Cash Equivalents + References No definition available. + Details
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- Definition Maturity of Resell Agreement Considered Cash Equivalents, Minimum + References No definition available. + Details
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Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

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- Definition Maturity of Resell Agreements Considered Cash Equivalents, Maximum + References No definition available. + Details
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Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

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- References No definition available. + Details
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