Shareholders' Equity (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Common stock, authorized (in shares)	2,500,000,000		2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006		$ 0.00006
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	$ 128,979,000		$ 107,839,000		$ (10,740,000)
Net change in unrealized gain (loss)	66,197,000		47,287,000		185,463,000
Other-than-temporary impairment losses recognized in earnings	7,351,000		23,507,000		27,809,000
Transfer of unrealized gain from available for sale securities to investment (held-to-maturity) securities			0
Amortization of unrealized gain on investment securities transferred from AFS	(6,601,000)		(1,357,000)		0
Reclassification adjustment for net (gains) losses realized and included in earnings	(33,392,000)		(33,840,000)		(21,618,000)
Income tax expense (benefit)	(12,614,000)	[1]	(14,457,000)	[1]	(73,075,000)	[1]
Ending balance	149,920,000		128,979,000		107,839,000
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital Ratio Required to be Well Capitalized	10.00%		10.00%
Total Capital	2,877,949,000		2,851,099,000
Total Capital to Risk Weighted Assets	15.13%		16.49%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital Ratio Required to be Well Capitalized	6.00%		6.00%
Tier I Capital	2,430,671,000		2,295,061,000
Tier I Capital to Risk Weighted Assets	12.78%		13.27%
Tier I Capital (to Average Assets) [Abstract]
Leverage Ratio Required to be Well Capitalized	5.00%		5.00%
Tier I Capital to Average Assets	9.01%		9.15%
Unrealized Gain (Loss) On Available For Sale Securities [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	135,740,000		122,494,000		6,772,000
Net change in unrealized gain (loss)	58,921,000		45,593,000		181,051,000
Other-than-temporary impairment losses recognized in earnings	7,351,000		23,507,000		27,809,000
Transfer of net unrealized gain from AFS to Investment securities			(12,999,000)
Amortization of unrealized gain on investment securities transferred from AFS	0		0
Reclassification adjustment for net (gains) losses realized and included in earnings	(33,845,000)		(34,144,000)		(21,882,000)
Income tax expense (benefit)	(12,614,000)	[1]	(8,711,000)	[1]	(71,256,000)	[1]
Ending balance	155,553,000		135,740,000		122,494,000
Accumulated Loss on Effective Cash Flow Hedges [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(692,000)		(878,000)		(1,039,000)
Net change in unrealized gain (loss)	0		0		0
Other-than-temporary impairment losses recognized in earnings	0		0		0
Transfer of unrealized gain from available for sale securities to investment (held-to-maturity) securities			0
Amortization of unrealized gain on investment securities transferred from AFS	0		0
Reclassification adjustment for net (gains) losses realized and included in earnings	453,000		304,000		264,000
Income tax expense (benefit)	(176,000)	[1]	(118,000)	[1]	(103,000)	[1]
Ending balance	(415,000)		(692,000)		(878,000)
Unrealized Loss On Employee Benefit Plans [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	(12,742,000)		(13,777,000)		(16,473,000)
Net change in unrealized gain (loss)	7,276,000		1,694,000		4,412,000
Other-than-temporary impairment losses recognized in earnings	0		0		0
Transfer of unrealized gain from available for sale securities to investment (held-to-maturity) securities			0
Amortization of unrealized gain on investment securities transferred from AFS	0		0
Reclassification adjustment for net (gains) losses realized and included in earnings	0		0		0
Income tax expense (benefit)	(2,830,000)	[1]	(659,000)	[1]	(1,716,000)	[1]
Ending balance	(8,296,000)		(12,742,000)		(13,777,000)
Accumulated Unrealized Gain on AFS Securities Transferred to Investment Securities [Member]
Accumulated Other Comprehensive Income [Roll Forward]
Beginning balance	6,673,000		0		0
Net change in unrealized gain (loss)	0		0		0
Other-than-temporary impairment losses recognized in earnings	0		0		0
Transfer of unrealized gain from available for sale securities to investment (held-to-maturity) securities			12,999,000
Amortization of unrealized gain on investment securities transferred from AFS	(6,601,000)		(1,357,000)
Reclassification adjustment for net (gains) losses realized and included in earnings	0		0		0
Income tax expense (benefit)	3,006,000	[1]	(4,969,000)	[1]	0	[1]
Ending balance	3,078,000		6,673,000		0
BOKF, NA [Member]
Allowed dividends without regulatory approval	275,000,000		270,000,000		280,000,000
Maximum percentage of unimpaired capital on loan commitments and equity investments to a single affiliate (in hundredths)	10.00%
Maximum percentage of unimpaired capital on loan commitments and equity investments to all affiliates (in hundredths)	20.00%
Maximum loan commitments and equity investments to a single affiliate	230,000,000
Maximum loan commitments and equity investments to all affiliates	459,000,000
Largest loan commitment and equity investment to a single affiliate	220,000,000
Aggregate loan commitment and equity investment to all affiliates	330,000,000		323,000,000
Largest amount outstanding to a single affiliate	65,000,000
Outstanding amounts to all affiliates	81,000,000		50,000,000
Total Capital (to Risk Weighted Assets) [Abstract]
Total Capital	2,296,451,000		2,329,670,000
Total Capital to Risk Weighted Assets	12.13%		13.53%
Tier I Capital (to Risk Weighted Assets) [Abstract]
Tier I Capital	1,849,769,000		1,775,182,000
Tier I Capital to Risk Weighted Assets	9.77%		10.31%
Tier I Capital (to Average Assets) [Abstract]
Tier I Capital to Average Assets	6.89%		7.11%
Other Non-Bank Subsidiaries [Member]
Allowed dividends without regulatory approval	48,000,000
Preferred Stock [Member]
Preferred stock, authorized (in shares)	1,000,000,000
Preferred stock at par value (in dollars per share)	$ 0.00005
Preferred stock conversion rate	one share of Common Stock for each 36 shares of Series A Preferred Stock at the option of the holder
Preferred stock, Rate of annual cumulative dividends (in hundredths)	10.00%
Preferred stock, Liquidation preference per share	$ 0.06
Aggregate liquidation preference	$ 15,000,000
Common Stock [Member]
Common stock, authorized (in shares)	2,500,000,000
Common stock, par value (in dollars per share)	$ 0.00006
Common stock, number of vote per share	$ 1

[1] 1 Calculated using 39% effective tax rate.