Loans and Allowance for Credit Losses Allowance for Loan Losses by Portfolio Segment (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	$ 170,233	$ 156,050	$ 160,537	$ 169,910
Loans and leases charged off	(10,128)	(6,883)	(20,208)	(55,440)
Recoveries of loans and leases previously charged off	3,814	3,842	11,300	8,475
Net loans and leases charged off	(6,314)	(3,041)	(8,908)	(46,965)
Provision for loan losses	2,216	4,801	14,506	34,865
Ending Balance	166,135	157,810	166,135	157,810
Provision for loan losses gross	46,000,000	3,200	(2,200)	3,800
Provision for credit losses	2,170	1,620	12,295	38,707
Real-estate - commercial mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	54,859	56,583	52,889	58,793
Loans and leases charged off	(394)	(650)	(1,769)	(1,283)
Recoveries of loans and leases previously charged off	444	928	749	1,528
Net loans and leases charged off	50	278	(1,020)	245
Provision for loan losses	(5,529)	(2,750)	(2,489)	(4,927)
Ending Balance	49,380	54,111	49,380	54,111
Commercial - industrial, financial and agricultural
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	66,341	59,045	58,868	66,280
Loans and leases charged off	(7,181)	(3,541)	(11,863)	(46,178)
Recoveries of loans and leases previously charged off	2,311	731	6,234	2,347
Net loans and leases charged off	(4,870)	(2,810)	(5,629)	(43,831)
Provision for loan losses	7,710	(301)	15,942	33,485
Ending Balance	69,181	55,934	69,181	55,934
Real-estate - home equity
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	18,981	16,247	18,911	18,127
Loans and leases charged off	(498)	(743)	(923)	(1,967)
Recoveries of loans and leases previously charged off	132	217	552	694
Net loans and leases charged off	(366)	(526)	(371)	(1,273)
Provision for loan losses	(662)	2,890	(587)	1,757
Ending Balance	17,953	18,611	17,953	18,611
Real estate - residential mortgage
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	18,892	14,504	18,921	16,088
Loans and leases charged off	(533)	(483)	(1,322)	(1,128)
Recoveries of loans and leases previously charged off	440	317	783	520
Net loans and leases charged off	(93)	(166)	(539)	(608)
Provision for loan losses	(109)	3,774	308	2,632
Ending Balance	18,690	18,112	18,690	18,112
Real estate - construction
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	4,928	5,988	5,061	6,620
Loans and leases charged off	(45)	(212)	(143)	(976)
Recoveries of loans and leases previously charged off	164	664	1,493	1,414
Net loans and leases charged off	119	452	1,350	438
Provision for loan losses	(664)	(961)	(2,028)	(1,579)
Ending Balance	4,383	5,479	4,383	5,479
Consumer
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	3,363	1,699	3,217	2,045
Loans and leases charged off	(877)	(672)	(2,355)	(2,276)
Recoveries of loans and leases previously charged off	216	390	1,005	1,015
Net loans and leases charged off	(661)	(282)	(1,350)	(1,261)
Provision for loan losses	798	1,429	1,633	2,062
Ending Balance	3,500	2,846	3,500	2,846
Equipment lease financing, other and overdrafts
Accounts, Notes, Loans and Financing Receivable [Line Items]
Beginning Balance	2,869	1,984	2,670	1,957
Loans and leases charged off	(600)	(582)	(1,833)	(1,632)
Recoveries of loans and leases previously charged off	107	595	484	957
Net loans and leases charged off	(493)	13	(1,349)	(675)
Provision for loan losses	672	720	1,727	1,435
Ending Balance	$ 3,048	$ 2,717	$ 3,048	$ 2,717