Loans and Allowances for Credit Losses Part 3 (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	$ 9,897,933		$ 9,362,898	$ 9,264,184
Non-Graded, Recorded Investment	1,934,434		1,906,845	1,860,385
Total	11,832,367		11,269,743	11,124,569
Related Allowance [Abstract]
Internally Risk Graded, Allowance	150,507		160,086	206,614
Non-Graded, Allowance	42,335		47,045	43,225
Allowance For Financing Receivable Total	233,756	231,669	253,481	271,456	286,611	292,971
Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,637,747		9,025,862	8,888,090
Non-Graded, Recorded Investment	1,912,618		1,882,048	1,834,789
Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	150,103		160,547	172,215
Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	110,083		176,489	203,879
Non-Graded, Recorded Investment	21,816		24,797	25,596
Commercial [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,255,739		6,536,602	6,402,534
Non-Graded, Recorded Investment	17,478		18,468	19,068
Total	7,273,217		6,555,070	6,421,602
Related Allowance [Abstract]
Internally Risk Graded, Allowance	80,676		82,263	105,695
Non-Graded, Allowance	1,103		1,180	3,849
Allowance For Financing Receivable Total	81,779		83,443	109,544
Commercial [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	7,168,133		6,394,362	6,239,266
Non-Graded, Recorded Investment	17,405		18,416	18,871
Commercial [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	65,917		73,481	79,729
Commercial [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	21,689		68,759	83,539
Non-Graded, Recorded Investment	73		52	197
Commercial [Member] | Energy [Member]
Recorded Investment [Abstract]
Total	2,433,473		2,005,041	1,749,203
Commercial [Member] | Energy [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,419,960		2,003,288	1,744,314
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Energy [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,450		1,417	989
Commercial [Member] | Energy [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,063		336	3,900
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Services [Member]
Recorded Investment [Abstract]
Total	1,891,728		1,761,538	1,872,947
Commercial [Member] | Services [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,847,177		1,713,232	1,820,569
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Services [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	34,452		31,338	34,197
Commercial [Member] | Services [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,099		16,968	18,181
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Wholesale/retail [Member]
Recorded Investment [Abstract]
Total	1,079,267		967,426	1,021,070
Commercial [Member] | Wholesale/retail [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,073,019		912,090	956,701
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Wholesale/retail [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,241		34,156	37,281
Commercial [Member] | Wholesale/retail [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,007		21,180	27,088
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Manufacturing [Member]
Recorded Investment [Abstract]
Total	363,092		336,733	373,074
Commercial [Member] | Manufacturing [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	350,340		311,292	342,878
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Manufacturing [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	10,469		2,390	2,505
Commercial [Member] | Manufacturing [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,283		23,051	27,691
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Integrated food services [Member]
Recorded Investment [Abstract]
Total	213,832		204,311	192,200
Commercial [Member] | Integrated food services [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	213,148		203,555	190,958
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Integrated food services [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	684		756	1,242
Commercial [Member] | Integrated food services [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Healthcare [Member]
Recorded Investment [Abstract]
Total	1,037,288		978,160	914,346
Commercial [Member] | Healthcare [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,033,799		969,260	905,129
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Healthcare [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	184		3,414	3,502
Commercial [Member] | Healthcare [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,305		5,486	5,715
Non-Graded, Recorded Investment	0		0	0
Commercial [Member] | Other commercial and industrial [Member]
Recorded Investment [Abstract]
Total	254,537		301,861	298,762
Commercial [Member] | Other commercial and industrial [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	230,690		281,645	278,717
Non-Graded, Recorded Investment	17,405		18,416	18,871
Commercial [Member] | Other commercial and industrial [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	5,437		10	13
Commercial [Member] | Other commercial and industrial [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	932		1,738	964
Non-Graded, Recorded Investment	73		52	197
Commercial Real Estate [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,165,489		2,291,303	2,272,833
Non-Graded, Recorded Investment	37		0	0
Total	2,165,526		2,291,303	2,272,833
Related Allowance [Abstract]
Internally Risk Graded, Allowance	60,704		67,034	91,712
Non-Graded, Allowance	0		0	0
Allowance For Financing Receivable Total	60,704		67,034	91,712
Commercial Real Estate [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,019,018		2,124,872	2,088,971
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	70,747		67,238	73,814
Commercial Real Estate [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	75,724		99,193	110,048
Non-Graded, Recorded Investment	37		0	0
Commercial Real Estate [Member] | Construction and land development [Member]
Recorded Investment [Abstract]
Total	289,544		342,054	370,465
Commercial Real Estate [Member] | Construction and land development [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	225,833		252,936	268,125
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Construction and land development [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	25,568		27,244	30,133
Commercial Real Estate [Member] | Construction and land development [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	38,143		61,874	72,207
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Retail [Member]
Recorded Investment [Abstract]
Total	525,051		509,402	457,176
Commercial Real Estate [Member] | Retail [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	510,163		499,295	448,076
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Retail [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	8,196		3,244	2,608
Commercial Real Estate [Member] | Retail [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	6,692		6,863	6,492
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Office [Member]
Recorded Investment [Abstract]
Total	406,007		405,923	422,284
Commercial Real Estate [Member] | Office [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	383,620		381,918	395,891
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Office [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	12,554		12,548	14,426
Commercial Real Estate [Member] | Office [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,833		11,457	11,967
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Multifamily [Member]
Recorded Investment [Abstract]
Total	398,513		369,028	388,304
Commercial Real Estate [Member] | Multifamily [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	388,701		357,436	375,253
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Multifamily [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	6,667		8,079	9,015
Commercial Real Estate [Member] | Multifamily [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	3,145		3,513	4,036
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Industrial [Member]
Recorded Investment [Abstract]
Total	187,166		278,186	224,222
Commercial Real Estate [Member] | Industrial [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	178,659		277,906	223,938
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Industrial [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,443		280	284
Commercial Real Estate [Member] | Industrial [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	4,064		0	0
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Other commercial real estate [Member]
Recorded Investment [Abstract]
Total	359,245		386,710	410,382
Commercial Real Estate [Member] | Other commercial real estate [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	332,042		355,381	377,688
Non-Graded, Recorded Investment	0		0	0
Commercial Real Estate [Member] | Other commercial real estate [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,319		15,843	17,348
Commercial Real Estate [Member] | Other commercial real estate [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	13,847		15,486	15,346
Non-Graded, Recorded Investment	37		0	0
Residential Mortgage [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	271,049		317,798	368,466
Non-Graded, Recorded Investment	1,747,931		1,656,729	1,581,435
Total	2,018,980		1,974,527	1,949,901
Related Allowance [Abstract]
Internally Risk Graded, Allowance	6,416		8,262	7,356
Non-Graded, Allowance	34,600		38,214	32,932
Allowance For Financing Receivable Total	41,016		46,476	40,288
Residential Mortgage [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	249,418		294,478	344,210
Non-Graded, Recorded Investment	1,728,519		1,634,403	1,558,607
Residential Mortgage [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	11,776		15,879	15,353
Residential Mortgage [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,855		7,441	8,903
Non-Graded, Recorded Investment	19,412		22,326	22,828
Residential Mortgage [Member] | Permanent mortgage [Member]
Recorded Investment [Abstract]
Total	1,134,519		1,153,644	1,180,310
Residential Mortgage [Member] | Permanent mortgage [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	249,418		294,478	344,210
Non-Graded, Recorded Investment	850,118		817,921	793,261
Residential Mortgage [Member] | Permanent mortgage [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	11,776		15,879	15,353
Residential Mortgage [Member] | Permanent mortgage [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,855		7,441	8,903
Non-Graded, Recorded Investment	13,352		17,925	18,583
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member]
Recorded Investment [Abstract]
Total	169,393		188,462	173,540
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	168,883		188,462	173,540
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Residential Mortgage [Member] | Permanent mortgages guaranteed by U.S. government agencies [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	510		0	0
Residential Mortgage [Member] | Home equity [Member]
Recorded Investment [Abstract]
Total	715,068		632,421	596,051
Residential Mortgage [Member] | Home equity [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	709,518		628,020	591,806
Residential Mortgage [Member] | Home equity [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Residential Mortgage [Member] | Home equity [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	5,550		4,401	4,245
Consumer [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	205,656		217,195	220,351
Non-Graded, Recorded Investment	168,988		231,648	259,882
Total	374,644		448,843	480,233
Related Allowance [Abstract]
Internally Risk Graded, Allowance	2,711		2,527	1,851
Non-Graded, Allowance	6,632		7,651	6,444
Allowance For Financing Receivable Total	9,343		10,178	8,295
Consumer [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	201,178		212,150	215,643
Non-Graded, Recorded Investment	166,694		229,229	257,311
Consumer [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,663		3,949	3,319
Consumer [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,815		1,096	1,389
Non-Graded, Recorded Investment	2,294		2,419	2,571
Consumer [Member] | Indirect automobile [Member]
Recorded Investment [Abstract]
Total	47,281		105,149	130,296
Consumer [Member] | Indirect automobile [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	45,349		102,955	127,878
Consumer [Member] | Indirect automobile [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Consumer [Member] | Indirect automobile [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	1,932		2,194	2,418
Consumer [Member] | Other consumer [Member]
Recorded Investment [Abstract]
Total	327,363		343,694	349,937
Consumer [Member] | Other consumer [Member] | Performing [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	201,178		212,150	215,643
Non-Graded, Recorded Investment	121,345		126,274	129,433
Consumer [Member] | Other consumer [Member] | Potential Problem [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	1,663		3,949	3,319
Consumer [Member] | Other consumer [Member] | Nonaccrual [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	2,815		1,096	1,389
Non-Graded, Recorded Investment	362		225	153
Allocated Class of Receivables [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	9,897,933		9,362,898	9,264,184
Non-Graded, Recorded Investment	1,934,434		1,906,845	1,860,385
Total	11,832,367		11,269,743	11,124,569
Related Allowance [Abstract]
Internally Risk Graded, Allowance	150,507		160,086	206,614
Non-Graded, Allowance	42,335		47,045	43,225
Allowance For Financing Receivable Total	192,842		207,131	249,839
Unallocated Financing Receivables [Member]
Recorded Investment [Abstract]
Internally Risk Graded, Recorded Investment	0		0	0
Non-Graded, Recorded Investment	0		0	0
Total	0		0	0
Related Allowance [Abstract]
Internally Risk Graded, Allowance	0		0	0
Non-Graded, Allowance	0		0	0
Allowance For Financing Receivable Total	$ 40,914	$ 40,858	$ 46,350	$ 21,617	$ 27,125	$ 26,736