The dollar amount of principal for mortgage loans being serviced for others.

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Data Type:	xbrli:monetaryItemType
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- Definition

Loans Serviced for Others that are less than 60 days past due but more than 29 days past due.

+ Details

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Data Type:	xbrli:monetaryItemType
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- Definition

Loans Serviced for Others that are less than 90 days past due but more than 59 days past due.

+ Details

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Namespace Prefix:	bokf
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The current portion dollar amount of principal for mortgage loans being serviced for others.

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Loans Serviced for Others that are equal to or greater than 90 days past due.

+ Details

Name:	bokf_LoansServicedForOtherstEqualToGreaterThan90DaysPastDue
Namespace Prefix:	bokf
Data Type:	xbrli:monetaryItemType
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- Details

Name:	bokf_StratificationOfMortgageLoanServicingPortfolioLineItems
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Balance Type:	na
Period Type:	duration

- Definition

Annual prepayment estimates based on loan interest rate , original term and loan type.

+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

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- Definition

Fair value as of the balance sheet date of an asset representing net future revenues 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 FASB Staff Position (FSP)

-Number FAS140-4/FIN46(R)-8

-Paragraph B9

-Subparagraph a(1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 13A, 13B

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 140

-Paragraph 17

-Subparagraph f(1)(a)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 4: 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=6863725&loc=d3e122625-111746

+ Details

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Mortgage Banking Activities, Loan Servicing Portfolio (Details) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Dec. 31, 2009
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Fair value	$ 87,948	$ 109,192	$ 115,723	$ 86,333	$ 98,942	$ 73,824
Outstanding principal of loans serviced	11,249,503
Weighted average prepayment rate (in hundredths)	22.87%
Loan Receivable Aging [Abstract]
Current	10,928,261
30 to 59 Days	201,401
60 to 89 Days	62,592
90 Days or More	57,249
Total	11,249,503
Interest Rate Range Less than 4.50% [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Fair value	13,444
Outstanding principal of loans serviced	1,503,755
Weighted average prepayment rate (in hundredths)	11.33%
Loan Receivable Aging [Abstract]
Total	1,503,755
Interest Rate Range 4.50% to 5.49% [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Fair value	55,105
Outstanding principal of loans serviced	5,464,857
Weighted average prepayment rate (in hundredths)	13.38%
Loan Receivable Aging [Abstract]
Total	5,464,857
Interest Rate Range 5.50% to 6.49% [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Fair value	15,508
Outstanding principal of loans serviced	3,079,400
Weighted average prepayment rate (in hundredths)	35.64%
Loan Receivable Aging [Abstract]
Total	3,079,400
Interest Rate Range Greater than 6.49% [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Fair value	3,891
Outstanding principal of loans serviced	1,201,491
Weighted average prepayment rate (in hundredths)	47.70%
Loan Receivable Aging [Abstract]
Total	1,201,491
FHLMC [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Outstanding principal of loans serviced	5,515,236
Loan Receivable Aging [Abstract]
Current	5,431,756
30 to 59 Days	46,728
60 to 89 Days	16,152
90 Days or More	20,600
Total	5,515,236
FNMA [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Outstanding principal of loans serviced	1,444,652
Loan Receivable Aging [Abstract]
Current	1,405,631
30 to 59 Days	23,053
60 to 89 Days	6,972
90 Days or More	8,996
Total	1,444,652
GNMA [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Outstanding principal of loans serviced	3,764,779
Loan Receivable Aging [Abstract]
Current	3,584,314
30 to 59 Days	122,544
60 to 89 Days	36,305
90 Days or More	21,616
Total	3,764,779
Other Investor Loans [Member]
Stratification of Mortgage Loan Servicing Portfolio [Line Items]
Outstanding principal of loans serviced	524,836
Loan Receivable Aging [Abstract]
Current	506,560
30 to 59 Days	9,076
60 to 89 Days	3,163
90 Days or More	6,037
Total	$ 524,836