Loans Part 1 (Details) (USD $)	6 Months Ended																				6 Months Ended
	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010	Jun. 30, 2011 Commercial Portfolio Segment [Member]	Dec. 31, 2010 Commercial Portfolio Segment [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Services Financing Receivable [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Energy Financing Receivable [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Wholesale Retail Financing Receivables [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Healthcare Financing Receivable [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Manufacturing Financing Receivable [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Other Commercial and Industrial [Member]	Jun. 30, 2011 Commercial Portfolio Segment [Member] Commercial Integrated Food Services Financing Receivables [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member]	Dec. 31, 2010 Commercial Real Estate Portfolio Segment [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Office Financing Receivables [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Retail Financing Receivables [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Other Real Estate Loans Financing Receivables [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Construction Financing Receivable [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Multifamily Financing Receivables [Member]	Jun. 30, 2011 Commercial Real Estate Portfolio Segment [Member] Commercial Real Estate Industrial [Member]	Jun. 30, 2010 Residential Portfolio Segment [Member]	Jun. 30, 2011 Residential Portfolio Segment [Member]	Dec. 31, 2010 Residential Portfolio Segment [Member]	Jun. 30, 2011 Consumer Portfolio Segment [Member]	Dec. 31, 2010 Consumer Portfolio Segment [Member]
Loan receivables disclosure [Abstract]
Loans receivables with fixed rate of interest	$ 4,915,532,000	$ 4,934,153,000		$ 2,830,388,000	$ 2,883,905,000								$ 872,696,000	$ 829,836,000								$ 920,063,000	$ 851,048,000	$ 292,385,000	$ 369,364,000
Loans receivables with variable rate of interest	5,621,842,000	5,478,069,000		3,294,843,000	3,011,636,000								1,200,656,000	1,297,148,000								916,241,000	939,774,000	210,102,000	229,511,000
Loan receivable non-accrual	200,170,000	230,814,000		53,365,000	38,455,000								110,363,000	150,366,000								31,693,000	37,426,000	4,749,000	4,567,000
Total	10,737,544,000	10,643,036,000	10,882,717,000	6,178,596,000	5,933,996,000								2,183,715,000	2,277,350,000								1,867,997,000	1,828,248,000	507,236,000	603,442,000
Accruing loans past due (90 days)	2,341,000	7,966,000
Loans receivable, other information [Abstract]
Amount of total loan portfolio to businesses and individuals in Oklahoma	4,800,000,000
Percentage of total loan portfolio to businesses and individuals in Oklahoma (in hundredths)	0.45
Amount of total loan portfolio to businesses and individuals in Texas	3,100,000,000
Percentage of total loan portfolio to businesses and individuals in Texas (in hundredths)	0.29
Amount of total loan portfolio provided to this classification						1,700,000,000	1,700,000,000	1,100,000,000	869,000,000	367,000,000	282,000,000	196,000,000			482,000,000	439,000,000	398,000,000	367,000,000	336,000,000	162,000,000
Percentage of total loan portfolio provided to this classification (in hundredths)						0.16	0.16
Amount Of loans with individual balances less than $10 million						1,000,000,000
Maximum loan amount for certain individual loans in category						10,000,000
Amount of loan portfolio to businesses in Oklahoma	2,600,000,000
Percentage of loan portfolio to businesses in Oklahoma (in hundredths)	0.42
Amount of loan portfolio to businesses in Texas	2,000,000,000
Percentage of loan portfolio to businesses in Texas (in hundredths)													0.32
Percentage of loan portfolio secured by property in Oklahoma (in hundredths)													0.28
Percentage of loan portfolio secured by property in Texas (in hundredths)	0.33
Minimum FICO required for jumbo loan approval																						720
Maximum debt-to-income ratio on jumbo loans (in hundredths)																						0.38
Minimum loan-to-value ratio on jumbo loans (in hundredths)																						0.6
Maximum loan-to-value ratio on jumbo loans (in hundredths)																						1
Minimum period for fixed rate on variable rate jumbo loans (in years)																						3 Y
Maximum period for fixed rate on variable rate jumbo loans (in years)																						10 Y
Amount of loan portfolio with modified terms																						22,000,000	22,000,000
Amount of loan portfolio with modified terms and guaranteed by US Government																						19,000,000	19,000,000
Amount of loans with modified terms that were 90 or more past due																						10,000,000
Number of days for past due loans (in days)	90 D																				90
Amount of loans guaranteed by US government and previously sold into GNMA mortgage pools																						109,000,000	48,000,000
Outstanding commitments to extend credit	5,500,000,000
Outstanding standby letters of credit	510,000,000
Outstanding commercial letters of credit	$ 7,000,000