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, 2016	Dec. 31, 2015
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	$ 105,400	$ 91,705
Other adjustments	(291)	(737)
Reclassification to/from allowance for unfunded lending-related commitments	(725)	(138)
Charge-offs	(24,691)	(25,507)
Recoveries	7,808	6,330
Provision for credit losses	34,790	33,747
Allowance for loan losses at period end	122,291	105,400
Allowance for unfunded lending-related commitments at period end	1,673	949
Allowance for credit losses at period end	123,964	106,349
Allowance for credit losses, Individually evaluated for impairment	6,903	6,418
Allowance for credit losses, Collectively evaluated for impairment	116,296	99,496
Loans, Individually evaluated for impairment	91,323	102,421
Loans, Collectively evaluated for impairment	19,169,557	16,466,006
Loans, net of unearned income	19,703,172	17,118,117
Commercial
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	36,135	31,699
Other adjustments	(90)	(51)
Reclassification to/from allowance for unfunded lending-related commitments	(500)	0
Charge-offs	(7,915)	(4,253)
Recoveries	1,594	1,432
Provision for credit losses	15,269	7,308
Allowance for loan losses at period end	44,493	36,135
Allowance for unfunded lending-related commitments at period end	500	0
Allowance for credit losses at period end	44,993	36,135
Allowance for credit losses, Individually evaluated for impairment	1,717	2,026
Allowance for credit losses, Collectively evaluated for impairment	42,624	34,025
Loans, Individually evaluated for impairment	20,790	18,789
Loans, Collectively evaluated for impairment	5,967,852	4,676,531
Loans, net of unearned income	6,005,422	4,713,909
Commercial real estate
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	43,758	35,533
Other adjustments	(154)	(419)
Reclassification to/from allowance for unfunded lending-related commitments	(225)	(138)
Charge-offs	(1,930)	(6,543)
Recoveries	2,945	2,840
Provision for credit losses	7,028	12,485
Allowance for loan losses at period end	51,422	43,758
Allowance for unfunded lending-related commitments at period end	1,173	949
Allowance for credit losses at period end	52,595	44,707
Allowance for credit losses, Individually evaluated for impairment	3,004	3,733
Allowance for credit losses, Collectively evaluated for impairment	49,552	40,625
Loans, Individually evaluated for impairment	42,309	59,871
Loans, Collectively evaluated for impairment	5,983,398	5,311,419
Loans, net of unearned income	6,196,087	5,529,289
Home equity
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	12,012	12,500
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(3,998)	(4,227)
Recoveries	484	312
Provision for credit losses	3,276	3,427
Allowance for loan losses at period end	11,774	12,012
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	11,774	12,012
Allowance for credit losses, Individually evaluated for impairment	1,233	333
Allowance for credit losses, Collectively evaluated for impairment	10,541	11,679
Loans, Individually evaluated for impairment	9,994	6,847
Loans, Collectively evaluated for impairment	715,799	777,828
Loans, net of unearned income	725,793	784,675
Residential real estate
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	4,734	4,218
Other adjustments	(57)	(125)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(1,730)	(2,903)
Recoveries	225	283
Provision for credit losses	2,542	3,261
Allowance for loan losses at period end	5,714	4,734
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	5,714	4,734
Allowance for credit losses, Individually evaluated for impairment	849	316
Allowance for credit losses, Collectively evaluated for impairment	4,792	4,416
Loans, Individually evaluated for impairment	17,735	16,522
Loans, Collectively evaluated for impairment	683,182	587,463
Loans, net of unearned income	705,221	607,451
Premium finance receivables
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	7,233	6,513
Other adjustments	10	(142)
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(8,193)	(7,060)
Recoveries	2,374	1,304
Provision for credit losses	6,201	6,618
Allowance for loan losses at period end	7,625	7,233
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	7,625	7,233
Allowance for credit losses, Individually evaluated for impairment	0	0
Allowance for credit losses, Collectively evaluated for impairment	7,625	7,233
Loans, Individually evaluated for impairment	0	0
Loans, Collectively evaluated for impairment	5,698,951	4,968,125
Consumer and other
Allowance for Loan Losses [Roll Forward]
Allowance for loan losses at beginning of period	1,528	1,242
Other adjustments	0	0
Reclassification to/from allowance for unfunded lending-related commitments	0	0
Charge-offs	(925)	(521)
Recoveries	186	159
Provision for credit losses	474	648
Allowance for loan losses at period end	1,263	1,528
Allowance for unfunded lending-related commitments at period end	0	0
Allowance for credit losses at period end	1,263	1,528
Allowance for credit losses, Individually evaluated for impairment	100	10
Allowance for credit losses, Collectively evaluated for impairment	1,162	1,518
Loans, Individually evaluated for impairment	495	392
Loans, Collectively evaluated for impairment	120,375	144,640
Loans, net of unearned income	122,041	146,376
Receivables Acquired with Deteriorated Credit Quality
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	765	435
Loans, net of unearned income	442,292	549,690
Receivables Acquired with Deteriorated Credit Quality | Commercial
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	652	84
Loans, net of unearned income	16,780	18,589
Receivables Acquired with Deteriorated Credit Quality | Commercial real estate
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	39	349
Loans, net of unearned income	170,380	157,999
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	73	2
Loans, net of unearned income	4,304	3,466
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	249,657	368,292
Receivables Acquired with Deteriorated Credit Quality | Consumer and other
Allowance for Loan Losses [Roll Forward]
Allowance for credit losses at period end	1	0
Loans, net of unearned income	$ 1,171	$ 1,344