Noninterest Income and Expenses - Summary of Noninterest Income and Expense (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Noninterest Income
Service charges on deposit accounts		$ 11,198	$ 10,049	$ 9,669
Trust fees		4,183	3,705	3,433
Mortgage banking fees		4,682	6,449	5,864
Brokerage commissions and fees		1,732	1,352	2,044
Marine finance fees		1,398	910	673
Interchange income		12,335	10,583	9,227
BOLI Income		4,291	3,426	2,213
Other		10,826	6,756	4,304
Noninterest Income		50,645	43,230	37,427
Securities (losses) gains, net		(623)	86	368
Gain on sale of Visa stock	$ 15,200	0	15,153	0
Total Noninterest Income		50,022	58,469	37,795
Noninterest Expenses
Salaries and wages		71,111	65,692	54,096
Employee benefits		12,945	11,732	9,903
Outsourced data processing costs		16,374	14,116	13,516
Telephone and data lines		2,481	2,291	2,108
Occupancy		13,394	13,290	13,122
Furniture and equipment		6,744	6,067	4,720
Marketing		5,085	4,784	3,633
Legal and professional fees		9,961	11,022	9,596
FDIC assessments		2,195	2,326	2,365
Amortization of intangibles		4,300	3,361	2,486
Foreclosed property expense and net loss (gain) on sale		461	(300)	44
Early redemption cost for Federal Home Loan Bank advances		0	0	1,777
Other		17,222	15,535	13,515
Total Noninterest Expenses		$ 162,273	$ 149,916	$ 130,881