Loans (Financing Receivables Credit Quality Indicators) (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014
Originated Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 12,856,037	$ 12,493,812	$ 10,826,913
Originated Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,317,897	5,175,201	4,476,156
Originated Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,133,017	2,117,118	2,247,285
Originated Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	580,978	537,766	359,751
Originated Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	388,873	370,179	257,509
Originated Loans | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	8,420,765	8,200,264	7,340,701
Originated Loans | Grade One
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net			37,601
Originated Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	59,380	52,676	28,610
Originated Loans | Grade One | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	667	683	240
Originated Loans | Grade One | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	678	299
Originated Loans | Grade One | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	13,052	4,451	8,452
Originated Loans | Grade One | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	73,099	58,488
Originated Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	191,008	186,278	135,574
Originated Loans | Grade Two | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,368	3,454	3,797
Originated Loans | Grade Two | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade Two | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,782	14,959	3,620
Originated Loans | Grade Two | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	200,158	204,691	142,991
Originated Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,405,007	1,340,100	940,937
Originated Loans | Grade Three | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	339,027	294,281	329,377
Originated Loans | Grade Three | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	62,821	46,074	24,731
Originated Loans | Grade Three | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	69,686	71,908	58,397
Originated Loans | Grade Three | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,876,541	1,752,363	1,353,442
Originated Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,504,600	3,413,446	3,276,975
Originated Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,724,516	1,745,470	1,823,877
Originated Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	516,852	490,757	332,227
Originated Loans | Grade Four | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	297,790	277,277	179,795
Originated Loans | Grade Four | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	6,043,758	5,926,950	5,612,874
Originated Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	103,432	139,083	61,507
Originated Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	29,034	29,990	39,245
Originated Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	942	257	259
Originated Loans | Grade Five | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,307	1,389	6,857
Originated Loans | Grade Five | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	134,715	170,719	107,868
Originated Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	54,470	43,618	32,553
Originated Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	36,405	43,240	50,749
Originated Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	363	0	2,235
Originated Loans | Grade Six | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,256	195	388
Originated Loans | Grade Six | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	92,494	87,053	85,925
Originated Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade Seven | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade Seven | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade Seven | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade Seven | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,324,879	2,479,180	3,235,915
Acquired Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	420,810	449,254	711,632
Acquired Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	584,072	630,674	837,876
Acquired Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	6,288	6,971	13,370
Acquired Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,011,170	1,086,899	1,562,878
Acquired Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,069	1,076	700
Acquired Loans | Grade One | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade One | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade One | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade One | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,069	1,076	700
Acquired Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Two | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Two | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Two | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Two | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	22,875	20,891	37,829
Acquired Loans | Grade Three | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	24,834	24,867	24,177
Acquired Loans | Grade Three | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Three | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Three | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	47,709	45,758	62,006
Acquired Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	359,751	376,129	609,383
Acquired Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	496,213	532,447	696,070
Acquired Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,612	6,286	13,370
Acquired Loans | Grade Four | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Four | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	861,576	914,862	1,318,823
Acquired Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	15,363	23,268	43,721
Acquired Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	21,487	28,382	51,253
Acquired Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	685	0
Acquired Loans | Grade Five | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Five | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	36,850	52,335	94,974
Acquired Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	21,752	27,890	19,999
Acquired Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	41,538	44,978	66,376
Acquired Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	676	0	0
Acquired Loans | Grade Six | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Six | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	63,966	72,868	86,375
Acquired Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	289,968	331,122	491,037
Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	42,814	48,837	65,252
Covered Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	127,908	153,508	255,593
Covered Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	8,825	9,262	20,421
Covered Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	179,547	211,607	341,266
Covered Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,040	1,347	957
Covered Loans | Grade Two | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Two | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Two | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Two | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,040	1,347	957
Covered Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Three | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Three | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Three | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Three | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	33,352	36,406	42,228
Covered Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	74,128	86,779	111,610
Covered Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	579	823	653
Covered Loans | Grade Four | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Four | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	108,059	124,008	154,491
Covered Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	39	167	387
Covered Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,134	3,401	2,883
Covered Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Five | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Five | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,173	3,568	3,270
Covered Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	8,383	10,917	19,864
Covered Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	51,646	63,328	140,927
Covered Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	8,246	8,248	19,459
Covered Loans | Grade Six | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Six | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	68,275	82,493	180,250
Covered Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	1,816
Covered Loans | Grade Seven | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	173
Covered Loans | Grade Seven | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	191	309
Covered Loans | Grade Seven | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Seven | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 0	$ 191	$ 2,298