Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended	12 Months Ended
Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Selected segment information
Net interest income	$ 154,123	$ 159,793	$ 307,846	$ 329,015
Provision for loan losses	16,000	97,665	47,000	263,010
Noninterest income	70,523	86,473	148,574	190,034
Depreciation and amortization	14,837	14,271	29,911	28,596
Other noninterest expense	149,817	146,349	304,788	289,406
Income taxes	9,610	(9,240)	17,486	(32,795)
Net income (loss)	34,382	(2,779)	57,235	(29,168)	(856)
% of consolidated net income (loss)	100.00%	0.00%	100.00%	0.00%
Total assets	22,048,475	22,760,059	22,048,475	22,760,059	21,785,596
% of consolidated total assets	100.00%	100.00%	100.00%	100.00%
Total revenues	224,646	246,266	456,420	519,049
% of consolidated total revenues	100.00%	100.00%	100.00%	100.00%
Banking segment [Member]
Selected segment information
Net interest income	154,008	159,619	307,599	328,631
Provision for loan losses	16,000	97,665	47,000	263,010
Noninterest income	45,803	62,485	100,211	142,092
Depreciation and amortization	14,547	13,959	29,326	27,972
Other noninterest expense	128,020	126,574	263,058	250,651
Income taxes	8,511	(10,870)	14,968	(36,374)
Net income (loss)	32,733	(5,224)	53,458	(34,536)
% of consolidated net income (loss)	95.00%	0.00%	93.00%	0.00%
Total assets	21,990,882	22,700,950	21,990,882	22,700,950
% of consolidated total assets	100.00%	100.00%	100.00%	100.00%
Total revenues	199,811	222,104	407,810	470,723
% of consolidated total revenues	89.00%	90.00%	89.00%	91.00%
Wealth segment [Member]
Selected segment information
Net interest income	115	174	247	384
Noninterest income	27,081	25,086	53,084	50,100
Depreciation and amortization	290	312	585	624
Other noninterest expense	24,158	20,873	46,451	40,913
Income taxes	1,099	1,630	2,518	3,579
Net income (loss)	1,649	2,445	3,777	5,368
% of consolidated net income (loss)	5.00%	0.00%	7.00%	0.00%
Total assets	143,676	132,060	143,676	132,060
% of consolidated total assets	0.00%	0.00%	0.00%	0.00%
Total revenues	27,196	25,260	53,331	50,484
% of consolidated total revenues	12.00%	10.00%	12.00%	9.00%
Other [Member]
Selected segment information
Noninterest income	(2,361)	(1,098)	(4,721)	(2,158)
Other noninterest expense	(2,361)	(1,098)	(4,721)	(2,158)
% of consolidated net income (loss)	0.00%	0.00%		0.00%
Total assets	(86,083)	(72,951)	(86,083)	(72,951)
% of consolidated total assets	0.00%	0.00%	0.00%	0.00%
Total revenues	$ (2,361)	$ (1,098)	$ (4,721)	$ (2,158)
% of consolidated total revenues	(1.00%)	0.00%	(1.00%)	0.00%

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