XML 62 R52.htm IDEA: XBRL DOCUMENT
v3.10.0.1

Mortgage Banking Activities, Mortgage Servicing Rights (Details) | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2018 USD ($) | Mar. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Jun. 30, 2017 USD ($) | Jun. 30, 2018 USD ($) | Jun. 30, 2017 USD ($)
Summary of Mortgage Servicing Rights [Abstract] |  |  |  |  |  |
Number of residential mortgage loans serviced for others | 134,868 |  | 136,528 | 138,335 | 134,868 | 138,335
Outstanding principal balance of residential mortgage loans serviced for others | $ 21,963,309,000 |  | $ 22,046,632,000 | $ 22,095,232,000 | $ 21,963,309,000 | $ 22,095,232,000
Weighted average interest rate | 3.96% |  | 3.94% | 3.95% | 3.96% | 3.95%
Remaining term (in months) | 295 months | 297 months |  | 299 months |  |
Servicing Asset at Fair Value, Amount [Roll Forward] |  |  |  |  |  |
Beginning balance | $ 274,978,000 | $ 252,867,000 |  | $ 249,403,000 | $ 252,867,000 | $ 247,073,000
Additions, net | 10,820,000 |  |  | 11,078,000 | 19,720,000 | 19,514,000
Change in fair value due to principal payments | (8,802,000) |  |  | (8,299,000) | (16,797,000) | (16,261,000)
Change in fair value due to market assumption changes | 1,723,000 |  |  | (6,943,000) | 22,929,000 | (5,087,000)
Ending balance | $ 278,719,000 | $ 274,978,000 | $ 252,867,000 | $ 245,239,000 | $ 278,719,000 | $ 245,239,000
Servicing Assets at Fair Value, Assumptions Used to Estimate Fair Value [Abstract] |  |  |  |  |  |
Discount rate - risk-free rate plus a market premium (in hundredths) | 9.91% |  | 9.84% | 9.84% |  |
Prepayment rate - based upon loan interest rate, original term and loan type, minimum | 8.12% |  | 8.72% | 8.61% |  |
Prepayment rate - based upon loan interest rate, original term and loan type, maximum | 15.08% |  | 15.16% | 15.91% |  |
Loan servicing costs - annually per loan based upon loan type, performing, minimum (in dollars per loan) | $ 65 |  | $ 65 | $ 65 |  |
Loan servicing costs - annually per loan based upon loan type, performing, maximum (in dollars per loan) | 88 |  | 88 | 120 |  |
Loan servicing costs - annually per loan based upon loan type, delinquent, minimum (in dollars per loan) | 150 |  | 150 | 150 |  |
Loan servicing costs - annually per loan based upon loan type, delinquent, maximum (in dollars per loan) | 500 |  | 500 | 500 |  |
Loan servicing costs - annually per loan based upon loan type, foreclosure, minimum (in dollars per loan) | 1,000 |  | 1,000 | 1,000 |  |
Loan servicing costs - annually per loan based upon loan type, foreclosure, maximum (in dollars per loan) | $ 4,000 |  | $ 4,000 | $ 4,250 |  |
Escrow earnings rate - indexed to rates paid on deposit accounts with comparable average life (in hundredths) | 2.88% |  | 2.24% | 1.95% |  |
Primary secondary mortgage rate spread (in basis points) | 105 |  | 105 | 105 | 105 | 105

X
- Definition The decrease in fair value as a result of loan runoff. + References No definition available. + Details
Name: | bokf_ChangeInFairValueDueToLoanRunoff
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Mortgage rate spread between the primary and secondary market. + References No definition available. + Details
Name: | bokf_Primarysecondarymortgageratespread
Namespace Prefix: | bokf_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Indicates the number of mortgage loans being serviced. + References No definition available. + Details
Name: | bokf_ResidentialMortgageLoansServicedNumberOfLoans
Namespace Prefix: | bokf_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Dollar amount of principal outstanding on mortgage loans being serviced. + References No definition available. + Details
Name: | bokf_ResidentialMortgageLoansServicedOutstandingPrincipal
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Represents the weighted average remaining term of mortgage loans being serviced fro others. + References No definition available. + Details
Name: | bokf_ResidentialMortgageLoansServicedWeightedAverageRemainingTerm
Namespace Prefix: | bokf_
Data Type: | us-types:durationStringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Delinquent Loan Service Cost Minimum + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValueDelinquentLoanServiceCostMinimum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Delinquent + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValueDelinquentLoanSvcCostMaximum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The escrow earning rate used to estimate the fair value of servicing assets, based on rates paid on deposit accounts. + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValueEscrowEarningsRate
Namespace Prefix: | bokf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Servicing Assets At Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Maximum + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValueForeclosureLoanServiceCostMaximum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Servicing Assets at Fair Value Assumptions Used to Estimate Fair Value Foreclosure Loan Service Cost Minimum + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValueForeclosureLoanServiceCostMinimum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The maximum cost to service a performing loan for the period used as a variable in estimating fair value. + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValuePerformingLoanServiceCostMaximum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The minimum cost to service a performing loan for the period used as a variable in estimating fair value. + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValuePerformingLoanServiceCostMinimum
Namespace Prefix: | bokf_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The maximum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeedMaximum
Namespace Prefix: | bokf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The minimum estimated speed of prepayments of principal on financial assets which may be one of the factors applied in estimating the fair value of servicing assets. + References No definition available. + Details
Name: | bokf_ServicingAssetsAtFairValueAssumptionsUsedToEstimateFairValuePrepaymentSpeedMinimum
Namespace Prefix: | bokf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition -- None. No documentation exists for this element. -- + References No definition available. + Details
Name: | bokf_SummaryOfMortgageServicingRightsAbstract
Namespace Prefix: | bokf_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Represents the weighted average interest rate of loans servicedf for others as of the balance sheet date. + References No definition available. + Details
Name: | bokf_WeightedAverageInterestRateofLoansServicedforOthers
Namespace Prefix: | bokf_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount of increase (decrease) in fair value from changes in the assumptions or model used to calculate the fair value of a contract to service financial assets under which the benefits of servicing are expected to more than adequately compensate the servicer. + References No definition available. + Details
Name: | us-gaap_AssetAtFairValueChangesInFairValueResultingFromChangesInAssumptions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The value of new servicing assets, subsequently measured at fair value, acquired or created during the current period through purchases or from transfers of financial assets. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(2) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
Name: | us-gaap_ServicingAssetAtFairValueAdditions
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Fair value of an asset representing net future revenue from contractually specified servicing fees, late charges, and other ancillary revenues, in excess of future costs related to servicing arrangements. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122625-111746 + Details
Name: | us-gaap_ServicingAssetAtFairValueAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period. + References No definition available. + Details
Name: | us-gaap_ServicingAssetAtFairValueAmountRollForward
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

X
- Definition Discount rate used to estimate the fair value of servicing assets and servicing liabilities. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 50 -Section 50 -Paragraph 2 -Subparagraph (d) -URI http://asc.fasb.org/extlink&oid=68078379&loc=d3e122596-111746 + Details
Name: | us-gaap_ServicingAssetsAndServicingLiabilitiesAtFairValueAssumptionsUsedToEstimateFairValueDiscountRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration