Noninterest Income and Expense - Summary of Noninterest Income and Expense (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Noninterest income
Service charges on deposit accounts	$ 2,674	$ 2,435	$ 5,346	$ 4,857
Trust fees	1,039	917	2,060	1,797
Mortgage banking fees	1,336	1,272	2,738	2,824
Brokerage commissions and fees	461	351	820	728
Marine finance fees	446	326	1,019	460
Interchange income	3,076	2,785	6,018	5,419
BOLI income	1,066	757	2,122	1,490
Other income	2,671	1,624	5,044	2,797
Noninterest income, gross	12,769	10,467	25,167	20,372
Securities (losses)/gains, net	(48)	21	(150)	21
TOTAL NONINTEREST INCOME (Note H)	12,721	10,488	25,017	20,393
Noninterest expense
Salaries and wages	16,429	18,375	31,810	33,744
Employee benefits	3,034	2,935	6,115	6,003
Outsourced data processing costs	3,393	3,456	7,072	6,725
Telephone/data lines	643	648	1,255	1,180
Occupancy	3,316	4,421	6,433	7,578
Furniture and equipment	1,468	1,679	2,925	3,070
Marketing	1,344	1,074	2,596	1,996
Legal and professional fees	2,301	3,276	4,274	5,408
FDIC assessments	595	650	1,193	1,220
Amortization of intangibles	1,004	839	1,993	1,558
Net losses and disposition expense on other real estate owned	405	297	597	4
Other	4,314	3,975	9,147	7,885
Total	$ 38,246	$ 41,625	$ 75,410	$ 76,371