Allowance for Loan Losses Allowance for Losses on Lending-Related Commitments and Impaired Loans (Summary of Activity in the Allowance for Credit Losses by Loan Portfolio) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	$ 91,705	$ 96,922
Other adjustments	(737)	(824)
Reclassification to/from allowance for unfunded lending-related commitments	(138)	(56)
Charge-offs	(25,507)	(32,104)
Recoveries	6,330	4,878
Provision for credit losses	33,747	22,889
Allowance for loan losses at period end	105,400	91,705
Allowance for unfunded lending-related commitments at period end	949	775
Allowance for credit losses at period end	106,349	92,480
Allowance for credit losses, Individually evaluated for impairment	6,418	6,329
Allowance for credit losses, Collectively evaluated for impairment	99,496	85,940
Loans, Individually evaluated for impairment	102,421	128,687
Loans, Collectively evaluated for impairment	16,466,006	13,820,063
Loans, net of unearned income	17,118,117	14,409,398
Commercial
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	31,699	23,092
Other adjustments	(51)	(83)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(4,253)	(4,153)
Recoveries	1,432	1,198
Provision for credit losses	7,308	11,645
Allowance for loan losses at period end	36,135	31,699
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	36,135	31,699
Allowance for credit losses, Individually evaluated for impairment	2,026	1,936
Allowance for credit losses, Collectively evaluated for impairment	34,025	29,763
Loans, Individually evaluated for impairment	18,789	16,326
Loans, Collectively evaluated for impairment	4,676,531	3,898,845
Loans, net of unearned income	4,713,909	3,924,394
Commercial real estate
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	35,533	48,658
Other adjustments	(419)	(665)
Reclassification to/from allowance for unfunded lending-related commitments	(138)	(56)
Charge-offs	(6,543)	(15,788)
Recoveries	2,840	1,334
Provision for credit losses	12,485	2,050
Allowance for loan losses at period end	43,758	35,533
Allowance for unfunded lending-related commitments at period end	949	775
Allowance for credit losses at period end	44,707	36,308
Allowance for credit losses, Individually evaluated for impairment	3,733	3,260
Allowance for credit losses, Collectively evaluated for impairment	40,625	32,960
Loans, Individually evaluated for impairment	59,871	87,225
Loans, Collectively evaluated for impairment	5,311,419	4,362,816
Loans, net of unearned income	5,529,289	4,505,753
Home equity
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	12,500	12,611
Other adjustments	0	(3)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(4,227)	(3,895)
Recoveries	312	535
Provision for credit losses	3,427	3,252
Allowance for loan losses at period end	12,012	12,500
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	12,012	12,500
Allowance for credit losses, Individually evaluated for impairment	333	475
Allowance for credit losses, Collectively evaluated for impairment	11,679	12,025
Loans, Individually evaluated for impairment	6,847	6,399
Loans, Collectively evaluated for impairment	777,828	709,894
Loans, net of unearned income	784,675	716,293
Residential real estate
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	4,218	5,108
Other adjustments	(125)	(9)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(2,903)	(1,750)
Recoveries	283	335
Provision for credit losses	3,261	534
Allowance for loan losses at period end	4,734	4,218
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	4,734	4,218
Allowance for credit losses, Individually evaluated for impairment	316	632
Allowance for credit losses, Collectively evaluated for impairment	4,416	3,482
Loans, Individually evaluated for impairment	16,522	18,365
Loans, Collectively evaluated for impairment	587,463	462,943
Loans, net of unearned income	607,451	483,542
Premium finance receivables
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	6,513	5,583
Other adjustments	(142)	(64)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(7,060)	(5,726)
Recoveries	1,304	1,150
Provision for credit losses	6,618	5,570
Allowance for loan losses at period end	7,233	6,513
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	7,233	6,513
Allowance for credit losses, Individually evaluated for impairment	0	0
Allowance for credit losses, Collectively evaluated for impairment	7,233	6,513
Loans, Individually evaluated for impairment	0	0
Loans, Collectively evaluated for impairment	4,968,125	4,234,925
Consumer and other
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	1,242	1,870
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(521)	(792)
Recoveries	159	326
Provision for credit losses	648	(162)
Allowance for loan losses at period end	1,528	1,242
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	1,528	1,242
Allowance for credit losses, Individually evaluated for impairment	10	26
Allowance for credit losses, Collectively evaluated for impairment	1,518	1,197
Loans, Individually evaluated for impairment	392	372
Loans, Collectively evaluated for impairment	144,640	150,640
Loans, net of unearned income	146,376	151,012
Receivables Acquired with Deteriorated Credit Quality
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	435	211
Loans, net of unearned income	549,690	460,648
Receivables Acquired with Deteriorated Credit Quality | Commercial
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	84	0
Loans, net of unearned income	18,589	9,223
Receivables Acquired with Deteriorated Credit Quality | Commercial real estate
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	349	88
Loans, net of unearned income	157,999	55,712
Receivables Acquired with Deteriorated Credit Quality | Home equity
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	0	0
Loans, net of unearned income	0	0
Receivables Acquired with Deteriorated Credit Quality | Residential real estate
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	2	104
Loans, net of unearned income	3,466	2,234
Receivables Acquired with Deteriorated Credit Quality | Premium finance receivables
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	0	0
Loans, net of unearned income	368,292	393,479
Receivables Acquired with Deteriorated Credit Quality | Consumer and other
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	0	19
Loans, net of unearned income	$ 1,344	$ 0