Loans and Credit Quality (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Jun. 30, 2014	Dec. 31, 2013	Jun. 30, 2013	Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	$ (81,899)	$ 83,786	$ (81,899)	$ 83,786
Allowance for loan and lease losses	81,899	(83,786)	81,899	(83,786)	(82,149)	82,034	(90,643)	(91,968)
Allowance for Loan and Lease Losses, Write-offs	7,956	2,795	14,940	8,582
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,725	675	3,707	4,302
Provision for Loan and Lease Losses	(5,981)	(4,737)	(11,098)	3,902
Loans and Leases Receivable, Net of Deferred Income	11,574,885	4,383,393	11,574,885	4,383,393		4,312,352
Loans and Leases Receivable Net Of Deferred Income Covered And Noncovered	11,574,885	4,383,393	11,574,885	4,383,393
Mortgage Loans on Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	27,003	29,606	27,003	29,606
Financing Receivable, Individually Evaluated for Impairment	1,568		1,568
Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	5,917	3,545	5,917	3,545
Financing Receivable, Individually Evaluated for Impairment	119		119
Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	29,007	25,461	29,007	25,461
Financing Receivable, Individually Evaluated for Impairment	7,654		7,654
Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	1,157	1,939	1,157	1,939
Financing Receivable, Individually Evaluated for Impairment	34		34
Loans and Leases Receivable, Net of Deferred Income	108,408		108,408
Purchased Credit Impaired Loans and Leases [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance, Covered	18,815	23,235	18,815	23,235	16,626	21,793	27,397	26,069
Allowance for Loan and Lease Losses, Write-offs	108	0	4,712	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	0	5	51	38
Provision for Loan and Lease Losses	(2,297)	(4,167)	1,683	2,872
Financing Receivable, Allowance for Credit Losses, Acquired with Deteriorated Credit Quality	18,815	23,235	18,815	23,235
Loans and Leases Receivable, Net of Deferred Income	351,379	432,757	351,379	432,757		382,796
Financing Receivable, Acquired with Deteriorated Credit Quality	351,379	432,757	351,379	432,757
NonCovered [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	63,084	60,551	63,084	60,551	65,523	60,241	63,246	65,899
Allowance for Loan and Lease Losses, Write-offs	(7,848)	2,795	(10,228)	8,582
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,725	670	3,656	4,264
Provision for Loan and Lease Losses	(3,684)	570	(9,415)	(1,030)
Financing Receivable, Individually Evaluated for Impairment	9,375	9,715	9,375	9,715
Financing Receivable, Collectively Evaluated for Impairment	53,709	50,836	53,709	50,836
Loans and Leases Receivable, Net of Deferred Income	11,223,506	3,950,636	11,223,506	3,950,636		3,929,556
Financing Receivable, Individually Evaluated for Impairment	123,256	131,082	123,256	131,082
Financing Receivable, Collectively Evaluated for Impairment	11,100,250	3,819,554	11,100,250	3,819,554
NonCovered [Member] | Mortgage Loans on Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	27,003	29,606	27,003	29,606	22,276	26,078	31,804	38,700
Allowance for Loan and Lease Losses, Write-offs	395	281	976	3,840
Allowance for Loan and Lease Loss, Recovery of Bad Debts	1,312	152	1,949	1,665
Provision for Loan and Lease Losses	3,810	(2,069)	(48)	(6,919)
Financing Receivable, Individually Evaluated for Impairment		3,225		3,225
Financing Receivable, Collectively Evaluated for Impairment	25,435	26,381	25,435	26,381
Loans and Leases Receivable, Net of Deferred Income	5,398,244	2,548,932	5,398,244	2,548,932		2,422,107
Financing Receivable, Individually Evaluated for Impairment	59,729	90,329	59,729	90,329
Financing Receivable, Collectively Evaluated for Impairment	5,338,515	2,458,603	5,338,515	2,458,603
NonCovered [Member] | Real Estate Construction [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	5,917	3,545	5,917	3,545	4,302	4,298	3,432	3,221
Allowance for Loan and Lease Losses, Write-offs	0	0	0	0
Allowance for Loan and Lease Loss, Recovery of Bad Debts	24	179	112	514
Provision for Loan and Lease Losses	(1,591)	66	1,507	(190)
Financing Receivable, Individually Evaluated for Impairment		103		103
Financing Receivable, Collectively Evaluated for Impairment	5,798	3,442	5,798	3,442
Loans and Leases Receivable, Net of Deferred Income	283,067	188,872	283,067	188,872		207,779
Financing Receivable, Individually Evaluated for Impairment	12,692	14,878	12,692	14,878
Financing Receivable, Collectively Evaluated for Impairment	270,375	173,994	270,375	173,994
NonCovered [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	29,007	25,461	29,007	25,461	35,530	26,921	26,343	22,252
Allowance for Loan and Lease Losses, Write-offs	(7,282)	2,439	(9,049)	4,631
Allowance for Loan and Lease Loss, Recovery of Bad Debts	337	324	1,301	2,028
Provision for Loan and Lease Losses	(422)	(1,233)	(9,834)	(5,812)
Financing Receivable, Individually Evaluated for Impairment		6,147		6,147
Financing Receivable, Collectively Evaluated for Impairment	21,353	19,314	21,353	19,314
Loans and Leases Receivable, Net of Deferred Income	5,433,787	1,178,923	5,433,787	1,178,923		1,244,785
Financing Receivable, Individually Evaluated for Impairment	47,180	25,083	47,180	25,083
Financing Receivable, Collectively Evaluated for Impairment	5,386,607	1,153,840	5,386,607	1,153,840
NonCovered [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Recorded Investment [Line Items]
Loans and Leases Receivable, Allowance	1,157	1,939	1,157	1,939	3,415	2,944	1,667	1,726
Allowance for Loan and Lease Losses, Write-offs	171	75	203	111
Allowance for Loan and Lease Loss, Recovery of Bad Debts	52	15	294	57
Provision for Loan and Lease Losses	(2,139)	(332)	1,878	267
Financing Receivable, Individually Evaluated for Impairment		240		240
Financing Receivable, Collectively Evaluated for Impairment	1,123	1,699	1,123	1,699
Loans and Leases Receivable, Net of Deferred Income		33,909		33,909		54,885
Financing Receivable, Individually Evaluated for Impairment	3,655	792	3,655	792
Financing Receivable, Collectively Evaluated for Impairment	$ 104,753	$ 33,117	$ 104,753	$ 33,117