Loans Held for Investment (LHFI) and Allowance for Loan Losses, excluding Covered Loans Part 3 (Details) (USD $)	Mar. 31, 2012	Dec. 31, 2011
Financing Receivable Aging [Abstract]
Current	$ 5,638,505,000	$ 5,708,531,000
Past Due 30 - 89 Days	28,924,000	34,265,000
Nonaccrual	105,773,000	110,458,000
Total LHFI	5,774,753,000	5,857,484,000
Number of Days used as Baseline in Evaluating Collateral Documentation Exceptions For Loan Policy (in days)	90 D
Loan Amount Used as Baseline in Credit Quality Review For Loan Policy	1,000,000
Credit Amount Used as Baseline in Evaluating Residential Real Estate Development and Non-owner Occupied Commercial Real Estate For Loan Policy	100,000
Charge-off Amount Used as Baseline in Credit Quality Review For Loan Policy	25,000
Construction Land Development And Other Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Total LHFI	465,486,000	474,082,000
Residential Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Total LHFI	1,722,357,000	1,760,930,000
Nonresidential Properties Financing Receivables [Member]
Financing Receivable Aging [Abstract]
Total LHFI	1,419,902,000	1,425,774,000
Other Real Estate Secured Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Total LHFI	199,400,000	204,849,000
Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	424,195,000	430,228,000
Past Due 30 - 89 Days	3,248,000	1,784,000
Nonaccrual	38,023,000	40,413,000
Total LHFI	465,486,000	474,082,000
Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	1,688,306,000	1,725,521,000
Past Due 30 - 89 Days	8,385,000	9,755,000
Nonaccrual	24,446,000	24,348,000
Total LHFI	1,722,357,000	1,760,930,000
Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member]
Financing Receivable Aging [Abstract]
Current	1,379,274,000	1,391,868,000
Past Due 30 - 89 Days	7,594,000	9,925,000
Nonaccrual	33,034,000	23,981,000
Total LHFI	1,419,902,000	1,425,774,000
Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	193,474,000	198,099,000
Past Due 30 - 89 Days	1,342,000	879,000
Nonaccrual	4,557,000	5,871,000
Total LHFI	199,400,000	204,849,000
Commercial And Industrial Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Total LHFI	1,142,813,000	1,139,365,000
Consumer Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	206,216,000	235,261,000
Past Due 30 - 89 Days	3,685,000	7,172,000
Nonaccrual	536,000	825,000
Total LHFI	210,713,000	243,756,000
Other Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	612,951,000	604,752,000
Past Due 30 - 89 Days	883,000	3,104,000
Nonaccrual	248,000	872,000
Total LHFI	614,082,000	608,728,000
Commercial Portfolio Segment [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	3,917,408,000	3,924,755,000
Commercial Portfolio Segment [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	3,546,281,000	3,554,041,000
Commercial Portfolio Segment [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	88,564,000	84,848,000
Commercial Portfolio Segment [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	281,506,000	284,694,000
Commercial Portfolio Segment [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	1,057,000	1,172,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	417,308,000	425,182,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	305,402,000	308,618,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	25,946,000	26,273,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	85,893,000	90,175,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	67,000	116,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	136,818,000	135,621,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	118,836,000	119,155,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	220,000	142,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	17,762,000	16,324,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	0
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	1,418,754,000	1,424,641,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	1,271,991,000	1,287,886,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	22,755,000	26,232,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	124,008,000	110,472,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	51,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	193,046,000	198,214,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	184,897,000	188,772,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	353,000	130,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	7,796,000	9,312,000
Commercial Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	0
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	1,141,598,000	1,137,584,000
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	1,057,620,000	1,048,556,000
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	39,290,000	32,046,000
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	43,910,000	56,577,000
Commercial Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	778,000	405,000
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	482,000	668,000
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	482,000	643,000
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	25,000
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	0
Commercial Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	0
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	609,402,000	602,845,000
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Pass [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	607,053,000	600,411,000
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Special Mention [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	0	0
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Substandard [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	2,137,000	1,834,000
Commercial Portfolio Segment [Member] | Other Loans Financing Receivable [Member] | Doubtful [Member]
Financing Receivable [Abstract]
Financing Receivable Commercial	212,000	600,000
Consumer Portfolio Segment [Member]
Financing Receivable Aging [Abstract]
Current	1,823,462,000	1,893,658,000
Past Due 30 - 89 Days	11,397,000	16,356,000
Past Due Greater Than 90 Days	1,518,000	1,804,000
Nonaccrual	20,968,000	20,911,000
Subtotal	1,857,345,000	1,932,729,000
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Construction Land Development And Other Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	46,801,000	47,253,000
Past Due 30 - 89 Days	238,000	353,000
Past Due Greater Than 90 Days	20,000	0
Nonaccrual	1,119,000	1,294,000
Subtotal	48,178,000	48,900,000
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Residential Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	1,557,701,000	1,596,800,000
Past Due 30 - 89 Days	7,359,000	8,477,000
Past Due Greater Than 90 Days	1,220,000	1,306,000
Nonaccrual	19,259,000	18,726,000
Subtotal	1,585,539,000	1,625,309,000
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Nonresidential Properties Financing Receivables [Member]
Financing Receivable Aging [Abstract]
Current	1,148,000	1,133,000
Past Due 30 - 89 Days	0	0
Past Due Greater Than 90 Days	0	0
Nonaccrual	0	0
Subtotal	1,148,000	1,133,000
Consumer Portfolio Segment [Member] | Real Estate Secured Financing Receivable [Member] | Other Real Estate Secured Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	6,327,000	6,405,000
Past Due 30 - 89 Days	0	201,000
Past Due Greater Than 90 Days	0	0
Nonaccrual	27,000	29,000
Subtotal	6,354,000	6,635,000
Consumer Portfolio Segment [Member] | Commercial And Industrial Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	1,167,000	1,626,000
Past Due 30 - 89 Days	38,000	118,000
Past Due Greater Than 90 Days	0	0
Nonaccrual	10,000	37,000
Subtotal	1,215,000	1,781,000
Consumer Portfolio Segment [Member] | Consumer Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	205,638,000	234,593,000
Past Due 30 - 89 Days	3,762,000	7,172,000
Past Due Greater Than 90 Days	278,000	498,000
Nonaccrual	553,000	825,000
Subtotal	210,231,000	243,088,000
Consumer Portfolio Segment [Member] | Other Loans Financing Receivable [Member]
Financing Receivable Aging [Abstract]
Current	4,680,000	5,848,000
Past Due 30 - 89 Days	0	35,000
Past Due Greater Than 90 Days	0	0
Nonaccrual	0	0
Subtotal	$ 4,680,000	$ 5,883,000