Loans, Allowance for Loan and Lease Losses, and Reserve for Off-Balance Sheet Credit Commitments (Details 4) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Allowance for Loan and Lease Losses
Beginning Balance	$ 305,790	$ 282,328	$ 302,584	$ 277,888
Charge-offs	(13,153)	(3,086)	(15,661)	(5,109)
Recoveries	9,518	10,591	16,196	17,422
Net (charge-offs) recoveries	(3,635)	7,505	535	12,313
(Reversal of) provision for credit losses	(1,000)		(1,000)
Transfers from reserve for off-balance sheet credit commitments	10,121	81	9,157	(287)
Ending Balance	311,276	289,914	311,276	289,914
Allowance individually evaluated for impairment	8,833	2,960	8,833	2,960
Allowance collectively evaluated for impairment	302,443	286,954	302,443	286,954
Loans and leases, excluding covered loans	18,474,788	15,819,252	18,474,788	15,819,252	17,170,438
Loans and leases, individually evaluated for impairment	89,615	118,529	89,615	118,529
Loans and leases, collectively evaluated for impairment	18,385,173	15,700,723	18,385,173	15,700,723
Provision for credit losses in the allowance			0	0
Reserve for Off Balance Sheet Credit Commitments
Balance, beginning of the year	34,908	25,205	33,944	24,837
Transfers (to) from allowance for loan and lease losses	(10,121)	(81)	(9,157)	287
Balance, end of the year	24,787	25,124	24,787	25,124
Commercial (includes lease financing)
Allowance for Loan and Lease Losses
Beginning Balance	121,574	112,748	117,103	104,731
Charge-offs	(12,862)	(2,869)	(14,821)	(4,231)
Recoveries	7,503	5,724	9,235	9,259
Net (charge-offs) recoveries	(5,359)	2,855	(5,586)	5,028
(Reversal of) provision for credit losses	711	1,016	5,409	6,860
Transfers from (to) reserve for off-balance sheet credit commitments	9,353		9,353
Ending Balance	126,279	116,619	126,279	116,619
Allowance individually evaluated for impairment	8,477	478	8,477	478
Allowance collectively evaluated for impairment	117,802	116,141	117,802	116,141
Loans and leases, excluding covered loans	8,837,544	7,497,105	8,837,544	7,497,105
Loans and leases, individually evaluated for impairment	29,231	34,915	29,231	34,915
Loans and leases, collectively evaluated for impairment	8,808,313	7,462,190	8,808,313	7,462,190
Commercial real estate mortgages
Allowance for Loan and Lease Losses
Beginning Balance	51,361	52,016	50,678	48,901
Charge-offs			(5)	(45)
Recoveries	27	1,034	127	1,082
Net (charge-offs) recoveries	27	1,034	122	1,037
(Reversal of) provision for credit losses	(737)	289	(149)	3,401
Ending Balance	50,651	53,339	50,651	53,339
Allowance individually evaluated for impairment	301	2,252	301	2,252
Allowance collectively evaluated for impairment	50,350	51,087	50,350	51,087
Loans and leases, excluding covered loans	3,464,918	2,978,975	3,464,918	2,978,975	3,223,001
Loans and leases, individually evaluated for impairment	33,456	41,932	33,456	41,932
Loans and leases, collectively evaluated for impairment	3,431,462	2,937,043	3,431,462	2,937,043
Residential mortgage
Allowance for Loan and Lease Losses
Beginning Balance	11,595	7,253	11,540	10,558
Charge-offs		(1)	(482)	(106)
Recoveries	190	38	225	75
Net (charge-offs) recoveries	190	37	(257)	(31)
(Reversal of) provision for credit losses	(1,489)	714	(987)	(2,523)
Ending Balance	10,296	8,004	10,296	8,004
Allowance individually evaluated for impairment	5	230	5	230
Allowance collectively evaluated for impairment	10,291	7,774	10,291	7,774
Loans and leases, excluding covered loans	4,814,435	4,153,051	4,814,435	4,153,051	4,554,311
Loans and leases, individually evaluated for impairment	10,596	7,979	10,596	7,979
Loans and leases, collectively evaluated for impairment	4,803,839	4,145,072	4,803,839	4,145,072
Real estate construction
Allowance for Loan and Lease Losses
Beginning Balance	6,468	9,962	6,351	11,784
Charge-offs		(100)		(100)
Recoveries	687	2,782	5,075	5,448
Net (charge-offs) recoveries	687	2,682	5,075	5,348
(Reversal of) provision for credit losses	36	(4,309)	(4,235)	(8,797)
Ending Balance	7,191	8,335	7,191	8,335
Allowance collectively evaluated for impairment	7,191	8,335	7,191	8,335
Loans and leases, excluding covered loans	457,557	340,002	457,557	340,002	367,004
Loans and leases, individually evaluated for impairment	12,846	30,446	12,846	30,446
Loans and leases, collectively evaluated for impairment	444,711	309,556	444,711	309,556
Home Equity Loans and Lines of Credit
Allowance for Loan and Lease Losses
Beginning Balance	6,419	4,843	6,677	7,283
Charge-offs	(149)	(35)	(165)	(275)
Recoveries	43	410	202	538
Net (charge-offs) recoveries	(106)	375	37	263
(Reversal of) provision for credit losses	262	182	(139)	(2,146)
Ending Balance	6,575	5,400	6,575	5,400
Allowance collectively evaluated for impairment	6,575	5,400	6,575	5,400
Loans and leases, excluding covered loans	716,816	700,681	716,816	700,681	709,344
Loans and leases, individually evaluated for impairment	3,436	3,257	3,436	3,257
Loans and leases, collectively evaluated for impairment	713,380	697,424	713,380	697,424
Installment
Allowance for Loan and Lease Losses
Beginning Balance	1,824	1,225	1,842	1,858
Charge-offs	(142)	(81)	(188)	(352)
Recoveries	1,068	603	1,332	1,020
Net (charge-offs) recoveries	926	522	1,144	668
(Reversal of) provision for credit losses	(466)	(392)	(702)	(1,171)
Ending Balance	2,284	1,355	2,284	1,355
Allowance individually evaluated for impairment	50		50
Allowance collectively evaluated for impairment	2,234	1,355	2,234	1,355
Loans and leases, excluding covered loans	183,518	149,438	183,518	149,438	151,955
Loans and leases, individually evaluated for impairment	50		50
Loans and leases, collectively evaluated for impairment	183,468	149,438	183,468	149,438
Qualitative
Allowance for Loan and Lease Losses
Beginning Balance	106,549	94,281	108,393	92,773
(Reversal of) provision for credit losses	683	2,500	(197)	4,376
Transfers from (to) reserve for off-balance sheet credit commitments	768	81	(196)	(287)
Ending Balance	108,000	96,862	108,000	96,862
Allowance collectively evaluated for impairment	$ 108,000	$ 96,862	$ 108,000	$ 96,862