Loans Financing receivables credit quality indicators (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2014	Dec. 31, 2013	Sep. 30, 2013
Covered Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 394,417	$ 530,143	$ 584,290
Covered Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	56,076	76,237	83,239
Covered Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	192,746	273,594	308,897
Covered Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	13,497	26,029	30,089
Covered Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Covered Loans | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	262,319	375,860	422,225
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 [Member]
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	1,373	968	996
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,373	968	996
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 [Member]
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	40,902	41,115	45,557
Covered Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	101,360	113,863	116,056
Covered Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	686	601	601
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	142,948	155,579	162,214
Covered Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,245	427	624
Covered Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,908	6,219	15,364
Covered Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	943
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,153	6,646	16,931
Covered Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	12,556	31,621	33,957
Covered Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	87,478	153,318	176,286
Covered Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	12,659	23,208	26,401
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	112,693	208,147	236,644
Covered Loans | Grade Seven | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	2,106	2,105
Covered Loans | Grade Seven | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	194	1,191
Covered Loans | Grade Seven | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	152	2,220	2,144
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	152	4,520	5,440
Acquired Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,745,104	3,495,615	3,817,421
Acquired Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	551,489	794,079	977,661
Acquired Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	710,495	918,645	967,903
Acquired Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	10,260	13,246	18,182
Acquired Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,272,244	1,725,970	1,963,746
Acquired Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Acquired Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	1,741	96
Acquired Loans | Grade Two | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	703	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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	2,444	96
Acquired Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	14,464	79,634	27,827
Acquired Loans | Grade Three | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	26,216	29,224	29,123
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	40,680	108,858	56,950
Acquired Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	492,667	643,495	849,858
Acquired Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	592,969	722,307	744,362
Acquired Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	10,260	13,246	18,182
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,095,896	1,379,048	1,612,402
Acquired Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	19,672	46,807	55,558
Acquired Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	44,570	93,499	102,256
Acquired Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	64,242	140,306	157,814
Acquired Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	24,686	22,402	44,322
Acquired Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	46,740	72,912	92,162
Acquired Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	71,426	95,314	136,484
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	0	0	0
Originated Loans
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	12,071,759	10,213,387	9,789,139
Originated Loans | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,039,320	4,139,567	3,864,095
Originated Loans | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	2,119,734	2,169,787	2,227,412
Originated Loans | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	467,112	338,925	328,862
Originated Loans | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	339,936	239,551	199,907
Originated Loans | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	7,966,102	6,887,830	6,620,276
Originated Loans | Grade One
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net			43,292
Originated Loans | Grade One | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	42,653	34,909	32,144
Originated Loans | Grade One | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	695	241	1,216
Originated Loans | Grade One | Commercial Real Estate Construction Financing Receivable
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	8,929	9,271	9,932
Originated Loans | Grade One | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	52,277	44,421
Originated Loans | Grade Two | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	214,307	108,709	82,906
Originated Loans | Grade Two | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,523	3,730	3,711
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	12,525	2,900	3,173
Originated Loans | Grade Two | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	230,355	115,339	89,790
Originated Loans | Grade Three | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,164,149	802,624	867,186
Originated Loans | Grade Three | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	285,652	315,150	368,918
Originated Loans | Grade Three | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	36,953	25,632	27,041
Originated Loans | Grade Three | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	58,157	54,446	29,631
Originated Loans | Grade Three | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,544,911	1,197,852	1,292,776
Originated Loans | Grade Four | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	3,458,074	3,083,458	2,796,101
Originated Loans | Grade Four | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,761,138	1,759,383	1,770,768
Originated Loans | Grade Four | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	420,721	306,795	300,154
Originated Loans | Grade Four | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	258,880	167,022	152,778
Originated Loans | Grade Four | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	5,898,813	5,316,658	5,019,801
Originated Loans | Grade Five | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	119,252	71,857	48,912
Originated Loans | Grade Five | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	29,410	34,969	30,502
Originated Loans | Grade Five | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	9,359	267	323
Originated Loans | Grade Five | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	1,233	5,750	3,325
Originated Loans | Grade Five | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	159,254	112,843	83,062
Originated Loans | Grade Six | Commercial and Industrial
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	40,885	38,010	36,846
Originated Loans | Grade Six | Commercial Real Estate Other Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	39,316	56,314	52,297
Originated Loans | Grade Six | Commercial Real Estate Construction Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	79	6,231	1,344
Originated Loans | Grade Six | Commercial Leases Financing Receivable
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	212	162	1,068
Originated Loans | Grade Six | Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	80,492	100,717	91,555
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 [Member]
Financing Receivable, Recorded Investment [Line Items]
Financing Receivable, Net	$ 0	$ 0	$ 0