Loans Part 2 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011	Dec. 31, 2011
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	$ 11,417,009	$ 10,392,393	$ 11,093,254
Individually measured for impairment, recorded investment	160,435	197,442	176,489
Total	11,577,444	10,589,835	11,269,743
Related allowance [Abstract]
Collectively measured for impairment, related allowance	197,522	254,542	201,355
Individually measured for impairment, related allowance	2,337	9,758	5,776
Total measured for impairment, related allowance - Ending balance	244,209	289,549
Allowance for loan losses [Roll Forward]
Beginning balance	253,481	292,971
Provision for loan losses	(787)	6,896
Loans charged off	(13,674)	(15,232)
Recoveries	5,189	4,914
Total measured for impairment, related allowance - Ending balance	244,209	289,549
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	9,261	14,271
Provision for off-balance sheet credit losses	787	(646)
Ending balance	10,048	13,625
Total provision for credit losses - Ending balance	0	6,250
Commercial Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	6,880,964	5,990,958	6,502,695
Individually measured for impairment, recorded investment	61,677	57,299	68,759
Total	6,942,641	6,048,257	6,571,454
Related allowance [Abstract]
Collectively measured for impairment, related allowance	85,508	109,020	81,907
Individually measured for impairment, related allowance	464	4,686	1,536
Total measured for impairment, related allowance - Ending balance	85,972	113,706
Allowance for loan losses [Roll Forward]
Beginning balance	83,443	104,631
Provision for loan losses	3,517	9,856
Loans charged off	(2,934)	(2,352)
Recoveries	1,946	1,571
Total measured for impairment, related allowance - Ending balance	85,972	113,706
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	7,906	13,456
Provision for off-balance sheet credit losses	456	(1,200)
Ending balance	8,362	12,256
Total provision for credit losses - Ending balance	3,973	8,656
Commercial Real Estate Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	2,177,628	2,097,478	2,180,716
Individually measured for impairment, recorded investment	86,475	125,504	99,193
Total	2,264,103	2,222,982	2,279,909
Related allowance [Abstract]
Collectively measured for impairment, related allowance	61,098	90,661	63,092
Individually measured for impairment, related allowance	1,644	3,874	3,942
Total measured for impairment, related allowance - Ending balance	62,742	94,535
Allowance for loan losses [Roll Forward]
Beginning balance	67,034	98,709
Provision for loan losses	1,121	2,376
Loans charged off	(6,725)	(6,893)
Recoveries	1,312	343
Total measured for impairment, related allowance - Ending balance	62,742	94,535
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	1,250	443
Provision for off-balance sheet credit losses	325	432
Ending balance	1,575	875
Total provision for credit losses - Ending balance	1,446	2,808
Residential Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	1,953,376	1,765,249	1,963,020
Individually measured for impairment, recorded investment	7,512	12,072	7,441
Total	1,960,888	1,777,321	1,970,461
Related allowance [Abstract]
Collectively measured for impairment, related allowance	34,484	44,540	38,909
Individually measured for impairment, related allowance	229	1,109	298
Total measured for impairment, related allowance - Ending balance	34,713	45,649
Allowance for loan losses [Roll Forward]
Beginning balance	39,207	50,281
Provision for loan losses	(3,119)	(2,766)
Loans charged off	(1,786)	(2,948)
Recoveries	411	1,082
Total measured for impairment, related allowance - Ending balance	34,713	45,649
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	91	131
Provision for off-balance sheet credit losses	(9)	24
Ending balance	82	155
Total provision for credit losses - Ending balance	(3,128)	(2,742)
Consumer Portfolio Segment [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	405,041	538,708	446,823
Individually measured for impairment, recorded investment	4,771	2,567	1,096
Total	409,812	541,275	447,919
Related allowance [Abstract]
Collectively measured for impairment, related allowance	16,432	10,321	17,447
Individually measured for impairment, related allowance	0	89	0
Total measured for impairment, related allowance - Ending balance	16,432	10,410
Allowance for loan losses [Roll Forward]
Beginning balance	17,447	12,614
Provision for loan losses	(306)	(1,083)
Loans charged off	(2,229)	(3,039)
Recoveries	1,520	1,918
Total measured for impairment, related allowance - Ending balance	16,432	10,410
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	14	241
Provision for off-balance sheet credit losses	15	98
Ending balance	29	339
Total provision for credit losses - Ending balance	(291)	(985)
Segment Allocations [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	11,417,009	10,392,393	11,093,254
Individually measured for impairment, recorded investment	160,435	197,442	176,489
Total	11,577,444	10,589,835	11,269,743
Related allowance [Abstract]
Collectively measured for impairment, related allowance	197,522	254,542	201,355
Individually measured for impairment, related allowance	2,337	9,758	5,776
Total measured for impairment, related allowance - Ending balance	199,859	264,300	207,131
Allowance for loan losses [Roll Forward]
Beginning balance			207,131
Total measured for impairment, related allowance - Ending balance	199,859	264,300	207,131
Unallocated Financing Receivables [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	0	0	0
Individually measured for impairment, recorded investment	0	0	0
Total	0	0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance	0	0	0
Individually measured for impairment, related allowance	0	0	0
Total measured for impairment, related allowance - Ending balance	44,350	25,249
Allowance for loan losses [Roll Forward]
Beginning balance	46,350	26,736
Provision for loan losses	(2,000)	(1,487)
Loans charged off	0	0
Recoveries	0	0
Total measured for impairment, related allowance - Ending balance	44,350	25,249
Allowance for off-balance sheet credit losses [Abstract]
Beginning balance	0	0
Provision for off-balance sheet credit losses	0	0
Ending balance	0	0
Total provision for credit losses - Ending balance	$ (2,000)	$ (1,487)

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