Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011 Y D business segment market	Sep. 30, 2010	Dec. 31, 2010
Business Segment Financial Information
Net interest income	$ 406,478	$ 409,962	$ 1,214,145	$ 1,203,511
Provision for credit losses	43,586	119,160	128,768	547,574
Noninterest income	258,559	267,143	751,271	777,638
Noninterest expense	439,118	427,309	1,298,226	1,239,213
Income taxes	38,942	29,690	122,667	4,915
Net income	143,391	100,946	415,755	189,447
Segment Disclosure of Assets and Deposit
Assets	54,978,707	53,246,776	54,978,707	53,246,776	53,819,642
Deposits	43,219,727	41,072,371	43,219,727	41,072,371	41,853,898
Segment Reporting (Textuals) [Abstract]
Number of reporting segments			4
Branches under retail and business banking network			over 600 branches
Number of ATM's			over 1,300
Company's definition of Business Banking by revenue size			less than $15 million
Number of business banking business			130,000
Number of Regional and Commercial Banking markets			11
Retail & Business Banking [Member]
Business Segment Financial Information
Net interest income	229,613	220,192	702,666	637,863
Provision for credit losses	36,467	59,316	94,825	150,320
Noninterest income	110,756	101,900	311,598	300,444
Noninterest expense	246,441	232,028	705,216	670,458
Income taxes	20,111	10,762	74,978	41,136
Net income	37,350	19,986	139,245	76,393
Segment Disclosure of Assets and Deposit
Assets	13,650,000	13,147,000	13,650,000	13,147,000	13,088,000
Deposits	28,095,000	28,735,000	28,095,000	28,735,000	29,298,000
Regional & Commercial Banking [Member]
Business Segment Financial Information
Net interest income	61,320	53,970	178,787	155,686
Provision for credit losses	16,530	3,731	23,957	57,607
Noninterest income	34,030	27,000	94,657	80,667
Noninterest expense	50,329	40,711	142,189	115,457
Income taxes	9,972	12,785	37,554	22,151
Net income	18,519	23,743	69,744	41,138
Segment Disclosure of Assets and Deposit
Assets	9,757,000	8,286,000	9,757,000	8,286,000	8,720,000
Deposits	4,173,000	3,217,000	4,173,000	3,217,000	3,538,000
AFCRE [Member]
Business Segment Financial Information
Net interest income	94,380	86,105	271,510	247,319
Provision for credit losses	(19,979)	37,132	(30,050)	202,440
Noninterest income	28,362	21,368	57,886	58,625
Noninterest expense	40,347	40,318	125,649	114,366
Income taxes	35,831	10,508	81,829	(3,802)
Net income	66,543	19,515	151,968	(7,060)
Segment Disclosure of Assets and Deposit
Assets	12,351,000	13,078,000	12,351,000	13,078,000	13,233,000
Deposits	817,000	776,000	817,000	776,000	753,000
WGH [Member]
Business Segment Financial Information
Net interest income	49,381	43,626	145,614	120,511
Provision for credit losses	10,568	18,983	40,036	45,700
Noninterest income	54,565	89,303	187,443	246,704
Noninterest expense	92,416	88,623	265,151	261,876
Income taxes	337	8,863	9,755	20,875
Net income	625	16,460	18,115	38,764
Segment Disclosure of Assets and Deposit
Assets	7,132,000	6,756,000	7,132,000	6,756,000	6,971,000
Deposits	9,013,000	7,247,000	9,013,000	7,247,000	7,449,000
Treasury/Other [Member]
Business Segment Financial Information
Net interest income	(28,216)	6,069	(84,432)	42,132
Provision for credit losses	0	(2)	0	91,507
Noninterest income	30,846	27,572	99,687	91,198
Noninterest expense	9,585	25,629	60,021	77,056
Income taxes	(27,309)	(13,228)	(81,449)	(75,445)
Net income	20,354	21,242	36,683	40,212
Segment Disclosure of Assets and Deposit
Assets	12,089,000	11,980,000	12,089,000	11,980,000	11,808,000
Deposits	$ 1,122,000	$ 1,097,000	$ 1,122,000	$ 1,097,000	$ 816,000