Fair Value Measurements, Financial Instruments (Details) (USD $) In Thousands, unless otherwise specified																6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended	6 Months Ended		12 Months Ended
	Jun. 30, 2012		Mar. 31, 2012	Dec. 31, 2011		Jun. 30, 2011		Mar. 31, 2011	Dec. 31, 2010	Jun. 30, 2012 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Dec. 31, 2011 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Jun. 30, 2011 Carrying (Reported) Amount, Fair Value Disclosure [Member]	Jun. 30, 2012 Estimate of Fair Value, Fair Value Disclosure [Member]	Dec. 31, 2011 Estimate of Fair Value, Fair Value Disclosure [Member]	Jun. 30, 2011 Estimate of Fair Value, Fair Value Disclosure [Member]	Jun. 30, 2012 Commercial [Member]	Jun. 30, 2011 Commercial [Member]	Dec. 31, 2011 Commercial [Member]	Jun. 30, 2012 Commercial Real Estate [Member]	Jun. 30, 2011 Commercial Real Estate [Member]	Dec. 31, 2011 Commercial Real Estate [Member]	Jun. 30, 2012 Residential Mortgage [Member]	Jun. 30, 2011 Residential Mortgage [Member]	Dec. 31, 2011 Residential Mortgage [Member]	Jun. 30, 2012 Consumer [Member]	Jun. 30, 2011 Consumer [Member]	Dec. 31, 2011 Consumer [Member]	Jun. 30, 2012 Time Deposits [Member]	Jun. 30, 2011 Time Deposits [Member]	Dec. 31, 2011 Time Deposits [Member]	Jun. 30, 2012 Other Borrowings [Member]	Jun. 30, 2011 Other Borrowings [Member]	Dec. 31, 2011 Other Borrowings [Member]	Jun. 30, 2012 Subordinated Debentures [Member]	Jun. 30, 2011 Subordinated Debentures [Member]	Dec. 31, 2011 Subordinated Debentures [Member]	Jun. 30, 2012 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2011 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]		Jun. 30, 2011 Fair Value, Inputs, Level 1 [Member] Fair Value, Measurements, Recurring [Member]		Jun. 30, 2012 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2011 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]		Jun. 30, 2011 Fair Value, Inputs, Level 2 [Member] Fair Value, Measurements, Recurring [Member]		Jun. 30, 2012 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Dec. 31, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]		Jun. 30, 2011 Fair Value, Inputs, Level 3 [Member] Fair Value, Measurements, Recurring [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 149,317			$ 76,800		$ 99,846																																	$ 0		$ 2,327				$ 76,623		$ 97,519				$ 177		$ 0
Cash and cash equivalents										639,263	986,365	1,110,761	639,263	986,365	1,110,761
US Government Obligations Trading Securities Fair Value Disclosure	53,514									53,514			53,514																								992						52,522						0
US Agency Residential Mortgage Backed Securities Trading Securities Fair Value Disclosure	46,502									46,502			46,502																								0						46,502						0
Municipals And Other Tax Exempt Trading Securities Fair Value Disclosure	44,632									44,632			44,632																								0						44,632						1,852
Other Trading Securities Fair Value Disclosure	4,669									4,669			4,669																								0						4,545						124
Trading Securities, Fair Value Disclosure	149,317									149,317	76,800	99,846	149,317	76,800	99,846																						992						148,201						1,976
Investment securities [Abstract]
Municipal and other tax-exempt										126,168	128,697	160,870	130,308	133,670	165,449
U.S. agency residential mortgage-backed securities										102,347	121,704		105,535	120,536
Other debt securities										183,964	188,835	188,713	204,795	208,451	203,798
Total investment securities	412,479			439,236		349,583				412,479	439,236	349,583	440,638	462,657	369,247
Available for sale securities [Abstract]
U.S. Treasury	1,003			1,006		1,003				1,003	1,006	1,003	1,003	1,006	1,003																						1,003		1,006		1,003		0		0		0		0		0		0
Municipal and other tax-exempt	88,458			68,837		70,210				88,458	68,837	70,210	88,458	68,837	70,210																						0		0		0		46,796		26,484		26,552		41,662		42,353		43,658
U.S. agency residential mortgage-backed securities	9,903,532			9,588,177		8,893,789				9,903,532	9,588,177	8,893,789	9,903,532	9,588,177	8,893,789																						0		0		0		9,903,532		9,588,177		8,893,789		0		0		0
Private issue residential mortgage-backed securities	317,761			419,166		513,222				317,761	419,166	513,222	317,761	419,166	513,222																						0		0		0		317,761		419,166		513,222		0		0		0
Other debt securities	36,286			36,495		5,893				36,286	36,495	5,893	36,286	36,495	5,893																						0		0		0		30,898		30,595		0		5,388		5,900		5,893
Perpetual preferred stock	23,431			18,446		22,694				23,431	18,446	22,694	23,431	18,446	22,694																						0		0		0		23,431		18,446		22,694		0		0		0
Equity securities and mutual funds	24,944			47,238		60,197				24,944	47,238	60,197	24,944	47,238	60,197																						6,912		23,596		41,557		18,032		23,642		18,640		0		0		0
Total available for sale securities	10,395,415			10,179,365		9,567,008				10,395,415	10,179,365	9,567,008	10,395,415	10,179,365	9,567,008																						7,915		24,602		42,560		10,340,450		10,106,510		9,474,897		47,050		48,253		49,551
Fair value option securities	325,177			651,226		553,231					651,226	553,231		651,226	553,231																								0		0				651,226		553,231				0		0
US Agency Residential Mortgage Backed Securities Fair Value Option Securities Fair Value Disclosure	299,467									299,467			299,467																								0						299,467						0
Corporate Debt Securities Fair Value Option Securities Fair Value Disclosure	25,710									25,710			25,710																								0						25,710						0
Total fair value option securities	325,177									325,177			325,177																								0						325,177						0
Residential mortgage loans held for sale	259,174			188,125		169,609				259,174	188,125	169,609	259,174	188,125	169,609																						0		0		0		259,174		188,125		169,609		0		0		0
Loans [Abstract]
Commercial										7,052,544	6,571,454	6,178,596	7,010,486	6,517,795	6,085,941
Commercial real estate										2,126,214	2,279,909	2,183,715	2,105,823	2,267,375	2,134,950
Residential mortgage										2,005,097	1,970,461	1,867,997	2,042,362	2,034,898	1,915,710
Consumer										392,576	447,919	507,236	387,423	436,490	507,831
Financial Instruments Interest Rate Risk Average Repricing																0.70	0.60	0.57	0.92	1.18	1.26	3.10	3.32	3.26	0.34	0.53	0.42	2.17	1.91	2.07	0.00	0.00	0.00	4.02	1.87	1.44
Total	11,576,431			11,269,743		10,737,544				11,576,431	11,269,743	10,737,544	11,546,094	11,256,558	10,644,432
Financial Instruments Discount Rate Range Maximum																3.92%	4.50%	3.85%	3.45%	3.66%	3.51%	3.86%	4.31%	3.70%	3.78%	3.74%	3.88%	1.44%	1.45%	1.43%	2.70%	2.65%	2.76%	2.40%	3.50%	3.29%
Allowance for loan losses	(231,669)		(244,209)	(253,481)		(286,611)		(289,549)	(292,971)	(231,669)	(253,481)	(286,611)	0	0	0
Loans, net of allowance	11,344,762			11,016,262		10,450,933				11,344,762	11,016,262	10,450,933	11,546,094	11,256,558	10,644,432
Mortgage servicing rights	91,783	[1]	98,138	86,783		109,192		120,345	115,723	91,783	86,783	109,192	91,783	86,783	109,192																						0	[1]	0		0		0	[1]	0		0		91,783	[1]	86,783	[1]	109,192	[1]
Derivative contracts, assets	366,204	[2],[3]		293,859	[2],[3]	229,887	[2],[3]			366,204	293,859	229,887	366,204	293,859	229,887																						802	[3]	457	[3]	0	[3]	365,402	[3]	293,402	[3]	229,887	[3]	0	[3]	0	[3]	0	[3]
Private equity funds, fair value disclosure	31,492			30,902		28,313																															0		0		0		0		0				31,492		30,902		28,313
Other assets - private equity funds										31,492	30,902	28,313	31,492	30,902	28,313
Deposits with no stated maturity										15,254,247	15,380,598	13,951,177	15,157,587	15,380,598	13,951,177
Time deposits	3,107,950			3,381,982		3,634,700				3,107,950	3,381,982	3,634,700	3,175,687	3,441,610	3,655,527
Other borrowings										2,648,753	2,370,867	2,962,759	2,642,598	2,369,224	2,962,773
Subordinated debentures	353,378			398,881		398,788				353,378	398,881	398,788	350,813	411,243	412,242
Derivative contracts, liabilities	$ 370,053	[2],[3]		$ 236,522	[2],[3]	$ 173,917	[2],[3]			$ 370,053	$ 236,522	$ 173,917	$ 370,053	$ 236,522	$ 173,917																						$ 251	[3]	$ 0	[3]	$ 0	[3]	$ 369,802	[3]	$ 236,522	[3]	$ 173,917	[3]	$ 0	[3]	$ 0	[3]	$ 0	[3]

[1] A reconciliation of the beginning and ending fair value of mortgage servicing rights and disclosures of significant assumptions used to determine fair value are presented in Note 5, Mortgage Banking Activities.

[2] Derivative contracts are recorded on a net basis in the balance sheet in recognition of master netting agreements that enable the Company to settle all derivative positions with a given counterparty in total and to offset the net derivative position with the related cash collateral.

[3] See Note 3 for detail of fair value of derivative contracts by contract type.