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Fair Value Measurements, Financial Instruments (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	$ 1,909,615		$ 462,676	$ 441,414
Investment securities	392,013		461,793	490,426
Available for sale securities	8,162,866		8,321,578	8,341,041
Fair value option securities	482,227		755,054	445,169
Residential mortgage loans held for sale	223,301		221,378	287,259
Loans	18,003,696		17,153,424	17,183,645
Allowance for loan losses	(215,142)	$ (223,967)	(230,682)	(250,061)	$ (248,710)	$ (246,159)
Loans, net of allowance	17,788,554		16,922,742	16,933,584
Mortgage servicing rights	278,719	274,978	252,867	245,239	249,403	247,073
Derviative contracts, net of cash collateral, Assets, Fair value	373,373		220,502	280,289
Time deposits	2,127,732		2,098,416	2,196,122
Subordinated debentures	144,697		144,677	144,658
Derivative contracts, net of cash collateral, Liabilities, Fair Value	234,856		171,963	285,819
Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	11,349,039		10,733,975	10,637,955
Allowance for loan losses	(113,722)	(120,083)	(124,269)	(137,742)	(137,616)	(140,213)
Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,712,220		3,479,987	3,688,592
Allowance for loan losses	(58,758)	(57,070)	(56,621)	(58,580)	(58,343)	(50,749)
Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,942,250		1,973,686	1,939,198
Allowance for loan losses	(18,544)	(18,431)	(18,451)	(18,259)	(18,177)	(18,224)
Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,000,187		965,776	917,900
Allowance for loan losses	(8,646)	$ (8,408)	(9,124)	(8,106)	$ (7,247)	$ (8,773)
U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	28,750		21,196	20,954
U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,605,001		392,673	365,171
Investment securities	13,989		15,891	18,035
Available for sale securities	5,304,560		5,309,152	5,382,377
Fair value option securities	482,227		755,054	445,169
Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	70,606		13,559	45,444
Investment securities	173,097		228,186	267,375
Available for sale securities	10,697		27,080	32,765
Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	11,987		11,363	9,845
U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	490		1,000	998
Privately issued residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	83,224		93,221	103,383
Commercial mortgage-backed securities guaranteed by U.S. government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	2,738,451		2,834,961	2,782,070
Other debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	204,927		217,716	205,016
Available for sale securities	25,444		25,481	4,152
Perpetual preferred stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			15,767	16,568
Equity securities and mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			14,916	18,728
Carrying (Reported) Amount, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	585,801		602,510	561,587
Interest-bearing cash and cash equivalents	872,999		1,714,544	2,078,831
Trading securities	1,909,615		462,676	441,414
Investment securities	392,013		461,793	490,426
Available for sale securities	8,162,866		8,321,578	8,341,041
Residential mortgage loans held for sale	223,301		221,378	287,259
Loans	18,003,696		17,153,424	17,183,645
Allowance for loan losses	(215,142)		(230,682)	(250,061)
Loans, net of allowance	17,788,554		16,922,742	16,933,584
Mortgage servicing rights	278,719		252,867	245,239
Derviative contracts, net of cash collateral, Assets, Fair value	373,373		220,502	280,289
Deposits with no stated maturity	20,041,532		19,962,889	20,120,352
Time deposits	2,127,732		2,098,416	2,196,122
Other borrowed funds	6,809,472		5,709,861	5,696,666
Subordinated debentures	144,697		144,677	144,658
Derivative contracts, net of cash collateral, Liabilities, Fair Value	234,856		171,963	285,819
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	11,349,039		10,733,975	10,637,955
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,712,220		3,479,987	3,688,592
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,942,250		1,973,686	1,939,198
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,000,187		965,776	917,900
Carrying (Reported) Amount, Fair Value Disclosure [Member] | U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	28,750		21,196	20,954
Carrying (Reported) Amount, Fair Value Disclosure [Member] | U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,605,001		392,673	365,171
Investment securities	13,989		15,891	18,035
Available for sale securities	5,304,560		5,309,152	5,382,377
Fair value option securities	482,227		755,054	445,169
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	70,606		13,559	45,444
Investment securities	173,097		228,186	267,375
Available for sale securities	10,697		27,080	32,765
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	193,271		23,885
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	11,987		11,363	9,845
Carrying (Reported) Amount, Fair Value Disclosure [Member] | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	490		1,000	998
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Privately issued residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	83,224		93,221	103,383
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	2,738,451		2,834,961	2,782,070
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Other debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	204,927		217,716	205,016
Available for sale securities	25,444		25,481	4,152
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Perpetual preferred stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			15,767	16,568
Carrying (Reported) Amount, Fair Value Disclosure [Member] | Equity securities and mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			14,916	18,728
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	585,801		602,510	561,587
Interest-bearing cash and cash equivalents	872,999		1,714,544	2,078,831
Trading securities	1,909,615		462,676	441,414
Investment securities	403,384		480,035	515,675
Available for sale securities	8,162,866		8,321,578	8,341,041
Residential mortgage loans held for sale	223,301		221,378	287,259
Loans	17,663,467		16,887,787	16,909,701
Allowance for loan losses	0		0	0
Loans, net of allowance	17,663,467		16,887,787	16,909,701
Mortgage servicing rights	278,719		252,867	245,239
Derviative contracts, net of cash collateral, Assets, Fair value	373,373		220,502	280,289
Deposits with no stated maturity	20,041,532		19,962,889	20,120,352
Time deposits	2,078,486		2,064,558	2,164,115
Other borrowed funds	6,571,762		5,703,121	5,664,273
Subordinated debentures	148,112		148,207	147,204
Derivative contracts, net of cash collateral, Liabilities, Fair Value	234,856		171,963	285,819
Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	11,116,828		10,524,627	10,413,704
Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,639,121		3,428,733	3,636,365
Estimate of Fair Value, Fair Value Disclosure [Member] | Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,917,099		1,977,721	1,950,577
Estimate of Fair Value, Fair Value Disclosure [Member] | Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	990,419		956,706	909,055
Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	28,750		21,196	20,954
Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,605,001		392,673	365,171
Investment securities	13,984		16,242	18,642
Available for sale securities	5,304,560		5,309,152	5,382,377
Fair value option securities	482,227		755,054	445,169
Estimate of Fair Value, Fair Value Disclosure [Member] | Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	70,606		13,559	45,444
Investment securities	174,205		230,349	270,531
Available for sale securities	10,697		27,080	32,765
Estimate of Fair Value, Fair Value Disclosure [Member] | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	193,271		23,885
Estimate of Fair Value, Fair Value Disclosure [Member] | Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	11,987		11,363	9,845
Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	490		1,000	998
Estimate of Fair Value, Fair Value Disclosure [Member] | Privately issued residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	83,224		93,221	103,383
Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	2,738,451		2,834,961	2,782,070
Estimate of Fair Value, Fair Value Disclosure [Member] | Other debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	215,195		233,444	226,502
Available for sale securities	25,444		25,481	4,152
Estimate of Fair Value, Fair Value Disclosure [Member] | Perpetual preferred stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			15,767	16,568
Estimate of Fair Value, Fair Value Disclosure [Member] | Equity securities and mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			14,916	18,728
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	585,801		602,510	561,587
Interest-bearing cash and cash equivalents	872,999		1,714,544	2,078,831
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	490		1,000	4,514
Residential mortgage loans held for sale	0		0	0
Loans	0		0	0
Allowance for loan losses	0		0	0
Loans, net of allowance	0		0	0
Mortgage servicing rights	0		0	0
Derviative contracts, net of cash collateral, Assets, Fair value	21,056		8,179	46,366
Deposits with no stated maturity	0		0	0
Time deposits	0		0	0
Other borrowed funds	0		0	0
Subordinated debentures	0		0	0
Derivative contracts, net of cash collateral, Liabilities, Fair Value	17,214		0	20,915
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	0		0	0
Fair value option securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	490		1,000	998
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Privately issued residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Other debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0		0	0
Available for sale securities	0		0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Perpetual preferred stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			0	0
Fair Value, Inputs, Level 1 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Equity securities and mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			0	3,516
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0		0	0
Interest-bearing cash and cash equivalents	0		0	0
Trading securities	1,909,615		462,676	441,414
Investment securities	403,384		480,035	515,675
Available for sale securities	8,159,875		8,315,304	8,327,720
Residential mortgage loans held for sale	209,058		209,079	274,524
Loans	0		0	0
Allowance for loan losses	0		0	0
Loans, net of allowance	0		0	0
Mortgage servicing rights	0		0	0
Derviative contracts, net of cash collateral, Assets, Fair value	352,317		212,323	233,923
Deposits with no stated maturity	0		0	0
Time deposits	0		0	0
Other borrowed funds	0		0	0
Subordinated debentures	148,112		148,207	147,204
Derivative contracts, net of cash collateral, Liabilities, Fair Value	217,642		171,963	264,904
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	0		0	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	28,750		21,196	20,954
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	1,605,001		392,673	365,171
Investment securities	13,984		16,242	18,642
Available for sale securities	5,304,560		5,309,152	5,382,377
Fair value option securities	482,227		755,054	445,169
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	70,606		13,559	45,444
Investment securities	174,205		230,349	270,531
Available for sale securities	8,667		22,278	28,110
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	193,271		23,885
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	11,987		11,363	9,845
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	0		0	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Privately issued residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	83,224		93,221	103,383
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial mortgage-backed securities guaranteed by U.S. government agencies
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities	2,738,451		2,834,961	2,782,070
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Other debt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	215,195		233,444	226,502
Available for sale securities	24,973		25,009	0
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Perpetual preferred stock
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			15,767	16,568
Fair Value, Inputs, Level 2 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Equity securities and mutual funds
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Available for sale securities			14,916	15,212
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Cash and due from banks	0		0	0
Interest-bearing cash and cash equivalents	0		0	0
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	2,501		5,274	8,807
Residential mortgage loans held for sale	14,243		12,299	12,735
Loans	17,663,467		16,887,787	16,909,701
Allowance for loan losses	0		0	0
Loans, net of allowance	17,663,467		16,887,787	16,909,701
Mortgage servicing rights	278,719		252,867	245,239
Derviative contracts, net of cash collateral, Assets, Fair value	0		0	0
Deposits with no stated maturity	20,041,532		19,962,889	20,120,352
Time deposits	2,078,486		2,064,558	2,164,115
Other borrowed funds	6,571,762		5,703,121	5,664,273
Subordinated debentures	0		0	0
Derivative contracts, net of cash collateral, Liabilities, Fair Value	0		0	0
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	11,116,828		10,524,627	10,413,704
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Commercial real estate
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	3,639,121		3,428,733	3,636,365
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Residential mortgage
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	1,917,099		1,977,721	1,950,577
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Personal
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Loans	990,419		956,706	909,055
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency debentures
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. government agency residential mortgage-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	0		0	0
Fair value option securities	0		0	0
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Municipal and other tax-exempt securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Investment securities	0		0	0
Available for sale securities	2,030		4,802	4,655
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Asset-backed securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Other trading securities
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Trading securities	0		0	0
Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | U.S. Treasury
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investment securities	0		0	0
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Fair Value, Inputs, Level 3 [Member] | Estimate of Fair Value, Fair Value Disclosure [Member] | Perpetual preferred stock
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Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
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