Loans Part 2 (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Dec. 31, 2011
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	$ 11,450,114	$ 10,561,213	$ 11,450,114	$ 10,561,213	$ 11,093,254
Individually measured for impairment, recorded investment	126,317	176,331	126,317	176,331	176,489
Total	11,576,431	10,737,544	11,576,431	10,737,544	11,269,743
Related allowance [Abstract]
Collectively measured for impairment, related allowance	188,976	252,803	188,976	252,803	201,355
Individually measured for impairment, related allowance	(1,835)	(6,683)	(1,835)	(6,683)	(5,776)
Total measured for impairment, related allowance	(231,669)	(286,611)	(231,669)	(286,611)
Allowance for loan losses [Roll Forward]
Beginning balance	244,209	289,549	253,481	292,971
Provision for loan losses	(7,699)	5,580	(8,486)	12,476
Loans charged off	(11,543)	(12,774)	(25,217)	(28,006)
Recoveries	6,702	4,256	11,891	9,170
Ending balance	231,669	286,611	231,669	286,611
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	10,048	13,625	9,261	14,271
Provision for off-balance sheet credit losses	(301)	(2,880)	486	(3,526)
Ending balance	9,747	10,745	9,747	10,745
Total provision for credit losses	(8,000)	2,700	(8,000)	8,950
Commercial [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	7,018,115	6,117,083	7,018,115	6,117,083	6,486,311
Individually measured for impairment, recorded investment	34,429	53,162	34,429	53,162	68,759
Total	7,052,544	6,170,245	7,052,544	6,170,245	6,555,070
Related allowance [Abstract]
Collectively measured for impairment, related allowance	83,199	111,131	83,199	111,131	81,907
Individually measured for impairment, related allowance	(278)	(2,440)	(278)	(2,440)	(1,536)
Total measured for impairment, related allowance	(83,477)	(113,571)	(83,477)	(113,571)
Allowance for loan losses [Roll Forward]
Beginning balance	85,972	113,706	83,443	104,631
Provision for loan losses	(2,526)	980	991	10,836
Loans charged off	(4,094)	(3,302)	(7,028)	(5,654)
Recoveries	4,125	2,187	6,071	3,758
Ending balance	83,477	113,571	83,477	113,571
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	8,362	12,256	7,906	13,456
Provision for off-balance sheet credit losses	(138)	(3,020)	318	(4,220)
Ending balance	8,224	9,236	8,224	9,236
Total provision for credit losses	(2,664)	(2,040)	1,309	6,616
Commercial Real Estate [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	2,046,006	2,077,668	2,046,006	2,077,668	2,192,110
Individually measured for impairment, recorded investment	80,208	110,363	80,208	110,363	99,193
Total	2,126,214	2,188,031	2,126,214	2,188,031	2,291,303
Related allowance [Abstract]
Collectively measured for impairment, related allowance	54,526	88,611	54,526	88,611	63,092
Individually measured for impairment, related allowance	(1,280)	(3,139)	(1,280)	(3,139)	(3,942)
Total measured for impairment, related allowance	(55,806)	(91,750)	(55,806)	(91,750)
Allowance for loan losses [Roll Forward]
Beginning balance	62,742	94,535	67,034	98,709
Provision for loan losses	(6,264)	289	(5,143)	2,665
Loans charged off	(1,216)	(3,380)	(7,941)	(10,273)
Recoveries	544	306	1,856	649
Ending balance	55,806	91,750	55,806	91,750
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	1,575	875	1,250	443
Provision for off-balance sheet credit losses	(150)	145	175	577
Ending balance	1,425	1,020	1,425	1,020
Total provision for credit losses	(6,414)	434	(4,968)	3,242
Residential Mortgage [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	1,997,887	1,861,069	1,997,887	1,861,069	1,967,086
Individually measured for impairment, recorded investment	7,210	10,885	7,210	10,885	7,441
Total	2,005,097	1,871,954	2,005,097	1,871,954	1,974,527
Related allowance [Abstract]
Collectively measured for impairment, related allowance	42,453	44,254	42,453	44,254	46,178
Individually measured for impairment, related allowance	(235)	(989)	(235)	(989)	(298)
Total measured for impairment, related allowance	(42,688)	(45,243)	(42,688)	(45,243)
Allowance for loan losses [Roll Forward]
Beginning balance	41,628	45,649	46,476	50,281
Provision for loan losses	4,371	2,721	898	(45)
Loans charged off	(4,061)	(3,381)	(5,847)	(6,329)
Recoveries	750	254	1,161	1,336
Ending balance	42,688	45,243	42,688	45,243
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	82	155	91	131
Provision for off-balance sheet credit losses	(2)	25	(11)	49
Ending balance	80	180	80	180
Total provision for credit losses	4,369	2,746	887	4
Consumer [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	388,106	505,393	388,106	505,393	447,747
Individually measured for impairment, recorded investment	4,470	1,921	4,470	1,921	1,096
Total	392,576	507,314	392,576	507,314	448,843
Related allowance [Abstract]
Collectively measured for impairment, related allowance	8,798	8,807	8,798	8,807	10,178
Individually measured for impairment, related allowance	(42)	(115)	(42)	(115)	0
Total measured for impairment, related allowance	(8,840)	(8,922)	(8,840)	(8,922)
Allowance for loan losses [Roll Forward]
Beginning balance	9,517	10,410	10,178	12,614
Provision for loan losses	212	(286)	260	(1,369)
Loans charged off	(2,172)	(2,711)	(4,401)	(5,750)
Recoveries	1,283	1,509	2,803	3,427
Ending balance	8,840	8,922	8,840	8,922
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	29	339	14	241
Provision for off-balance sheet credit losses	(11)	(30)	4	68
Ending balance	18	309	18	309
Total provision for credit losses	201	(316)	264	(1,301)
Segment Allocations [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	11,450,114	10,561,213	11,450,114	10,561,213	11,093,254
Individually measured for impairment, recorded investment	126,317	176,331	126,317	176,331	176,489
Total	11,576,431	10,737,544	11,576,431	10,737,544	11,269,743
Related allowance [Abstract]
Collectively measured for impairment, related allowance	188,976	252,803	188,976	252,803	201,355
Individually measured for impairment, related allowance	(1,835)	(6,683)	(1,835)	(6,683)	(5,776)
Total measured for impairment, related allowance	(190,811)	(259,486)	(190,811)	(259,486)	(207,131)
Allowance for loan losses [Roll Forward]
Beginning balance					207,131
Ending balance	190,811	259,486	190,811	259,486	207,131
Unallocated Financing Receivables [Member]
Recorded investment [Abstract]
Collectively measured for impairment, recorded investment	0	0	0	0	0
Individually measured for impairment, recorded investment	0	0	0	0	0
Total	0	0	0	0	0
Related allowance [Abstract]
Collectively measured for impairment, related allowance	0	0	0	0	0
Individually measured for impairment, related allowance	0	0	0	0	0
Total measured for impairment, related allowance	(40,858)	(27,125)	(40,858)	(27,125)
Allowance for loan losses [Roll Forward]
Beginning balance	44,350	25,249	46,350	26,736
Provision for loan losses	(3,492)	1,876	(5,492)	389
Loans charged off	0	0	0	0
Recoveries	0	0	0	0
Ending balance	40,858	27,125	40,858	27,125
Allowance for off-balance sheet credit losses [Roll Forward]
Beginning balance	0	0	0	0
Provision for off-balance sheet credit losses	0	0	0	0
Ending balance	0	0	0	0
Total provision for credit losses	$ (3,492)	$ 1,876	$ (5,492)	$ 389