Segment Information (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended															12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
OPERATIONS:
Net interest income	$ 120,966	$ 119,392		$ 117,443		$ 121,824		$ 127,864		$ 123,493		$ 116,767		$ 90,394		$ 479,627	$ 458,519	$ 348,764
Provision for loan losses																74,388	88,215	98,433
Other income																224,757	212,556	210,301
Other expenses																464,345	442,860	352,817
Net income	30,496	31,737	[1]	29,763	[1]	27,560	[1]	27,030	[1]	28,996	[1]	31,493	[1]	15,390	[1]	119,558	102,909	82,170
AVERAGES :
Assets	14,495,330							13,524,351								14,495,330	13,524,351	10,793,494
Loans	9,155,973							8,529,303								9,155,973	8,529,303	7,156,983
Earnings assets	12,728,724							11,756,985								12,728,724	11,756,985	9,925,234
Deposits	11,412,501							10,450,431								11,412,501	10,450,431	7,509,588
Economic Capital	1,548,353							1,315,621								1,548,353	1,315,621	1,049,925
Commercial [Member]
OPERATIONS:
Net interest income																265,196	250,597	154,504
Provision for loan losses																38,830	54,065	24,110
Other income																57,940	46,876	41,344
Other expenses																148,338	110,261	92,470
Net income																134,746	86,545	51,524
AVERAGES :
Assets	6,203,526							5,404,883								6,203,526	5,404,883	4,071,785
Loans	6,201,990							5,394,135								6,201,990	5,394,135	4,101,451
Earnings assets	6,281,589							5,456,316								6,281,589	5,456,316	4,135,791
Deposits	3,027,329							2,516,201								3,027,329	2,516,201	1,934,036
Economic Capital	368,434							308,547								368,434	308,547	258,925
Retail [Member]
OPERATIONS:
Net interest income																225,580	214,118	188,491
Provision for loan losses																21,672	36,249	60,780
Other income																103,248	114,497	104,212
Other expenses																235,339	224,334	194,848
Net income																62,048	44,220	24,098
AVERAGES :
Assets	2,935,699							2,983,395								2,935,699	2,983,395	2,864,636
Loans	2,661,910							2,698,502								2,661,910	2,698,502	2,685,133
Earnings assets	2,712,133							2,742,696								2,712,133	2,742,696	2,712,068
Deposits	7,500,213							7,015,468								7,500,213	7,015,468	4,708,554
Economic Capital	223,772							223,304								223,772	223,304	188,586
Wealth [Member]
OPERATIONS:
Net interest income																18,764	19,548	17,846
Provision for loan losses																3,479	2,668	8,085
Other income																31,684	32,596	32,342
Other expenses																40,004	39,604	37,838
Net income																7,122	6,416	2,771
AVERAGES :
Assets	240,952							278,143								240,952	278,143	306,690
Loans	227,710							266,522								227,710	266,522	297,589
Earnings assets	228,191							266,835								228,191	266,835	297,589
Deposits	644,879							578,876								644,879	578,876	533,039
Economic Capital	50,871							36,881								50,871	36,881	42,796
Other [Member]
OPERATIONS:
Net interest income																(29,913)	(25,744)	(12,077)
Provision for loan losses																10,407	(4,767)	5,458
Other income																31,885	18,587	32,403
Other expenses																40,664	68,661	27,661
Net income																(84,358)	(34,272)	3,777
AVERAGES :
Assets	5,115,153							4,857,930								5,115,153	4,857,930	3,550,383
Loans	64,363							170,144								64,363	170,144	72,810
Earnings assets	3,506,811							3,291,138								3,506,811	3,291,138	2,779,786
Deposits	240,080							339,886								240,080	339,886	333,959
Economic Capital	$ 905,276							$ 746,889								$ 905,276	$ 746,889	$ 559,618

[1] * Net income restated to reflect purchase accounting adjustments which decreased the bargain purchase gain recognized on the George Washington acquisition to $1.0 million in the quarter ended March 31, 2010.