Loans (Financing Receivables Credit Quality Indicators) (Details) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015	Mar. 31, 2015
Originated Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 14,389,513	$ 14,118,505	$ 12,856,037
Originated Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,837,315	5,793,408	5,317,897
Originated Loans | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,079,662	2,077,344	2,133,017
Originated Loans | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	670,825	645,337	580,978
Originated Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	512,929	491,741	388,873
Originated Loans | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	9,100,731	9,007,830	8,420,765
Originated Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	68,185	60,440	59,380
Originated Loans | Grade One | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	757	773	667
Originated Loans | Grade One | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans | Grade One | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	12,613	12,732	13,052
Originated Loans | Grade One | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	81,555	73,945	73,099
Originated Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	397,855	353,581	191,008
Originated Loans | Grade Two | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	818	831	3,368
Originated Loans | Grade Two | Construction Loans
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	43,507	69,258	5,782
Originated Loans | Grade Two | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	442,180	423,670	200,158
Originated Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,317,058	1,371,850	1,405,007
Originated Loans | Grade Three | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	310,816	319,987	339,027
Originated Loans | Grade Three | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	52,039	59,182	62,821
Originated Loans | Grade Three | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	80,042	49,956	69,686
Originated Loans | Grade Three | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,759,955	1,800,975	1,876,541
Originated Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,762,793	3,756,333	3,504,600
Originated Loans | Grade Four | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,719,833	1,697,261	1,724,516
Originated Loans | Grade Four | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	597,571	569,098	516,852
Originated Loans | Grade Four | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	336,402	344,763	297,790
Originated Loans | Grade Four | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	6,416,599	6,367,455	6,043,758
Originated Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	141,456	124,140	103,432
Originated Loans | Grade Five | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	9,924	18,388	29,034
Originated Loans | Grade Five | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,401	7,193	942
Originated Loans | Grade Five | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	32,416	7,858	1,307
Originated Loans | Grade Five | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	186,197	157,579	134,715
Originated Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	146,380	124,483	54,470
Originated Loans | Grade Six | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	37,514	40,105	36,405
Originated Loans | Grade Six | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	18,814	9,864	363
Originated Loans | Grade Six | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	7,949	7,174	1,256
Originated Loans | Grade Six | Commercial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	210,657	181,626	92,494
Originated Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,588	2,581	0
Originated Loans | Grade Seven | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	(1)	0
Originated Loans | Grade Seven | Construction Loans
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	3,588	2,580	0
Acquired Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,633,706	1,743,071	2,324,879
Acquired Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	230,700	240,145	420,810
Acquired Loans | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	391,863	430,891	584,072
Acquired Loans | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,467	6,113	6,288
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	628,030	677,149	1,011,170
Acquired Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	346	1,069
Acquired Loans | Grade One | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade One | Construction Loans
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	0	346	1,069
Acquired Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	596	0	0
Acquired Loans | Grade Two | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	615	0	0
Acquired Loans | Grade Two | Construction Loans
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	1,211	0	0
Acquired Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	27,818	15,548	22,875
Acquired Loans | Grade Three | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	23,221	27,387	24,834
Acquired Loans | Grade Three | Construction Loans
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	51,039	42,935	47,709
Acquired Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	169,906	200,736	359,751
Acquired Loans | Grade Four | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	327,406	361,518	496,213
Acquired Loans | Grade Four | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	4,749	5,380	5,612
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	502,061	567,634	861,576
Acquired Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	24,577	11,735	15,363
Acquired Loans | Grade Five | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	11,663	12,546	21,487
Acquired Loans | Grade Five | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	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	36,240	24,281	36,850
Acquired Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	7,803	11,780	21,752
Acquired Loans | Grade Six | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	28,958	29,440	41,538
Acquired Loans | Grade Six | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	718	733	676
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	37,479	41,953	63,966
Acquired Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Seven | Construction Loans
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	192,795	205,422	289,968
Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	31,930	35,466	42,814
Covered Loans | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	85,304	87,774	127,908
Covered Loans | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	4,889	5,869	8,825
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	122,123	129,109	179,547
Covered Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade One | Construction Loans
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	965	1,072	1,040
Covered Loans | Grade Two | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Two | Construction Loans
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	965	1,072	1,040
Covered Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Three | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	6,807	7,004	0
Covered Loans | Grade Three | Construction Loans
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	6,807	7,004	0
Covered Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	28,483	31,637	33,352
Covered Loans | Grade Four | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	48,512	49,917	74,128
Covered Loans | Grade Four | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	682	819	579
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	77,677	82,373	108,059
Covered Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	266	295	39
Covered Loans | Grade Five | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	2,134
Covered Loans | Grade Five | Construction Loans
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	266	295	2,173
Covered Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,216	2,462	8,383
Covered Loans | Grade Six | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	29,985	30,853	51,646
Covered Loans | Grade Six | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	4,207	5,050	8,246
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	36,408	38,365	68,275
Covered Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Seven | Real Estate Loan
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Grade Seven | Construction Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
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	$ 0	$ 0