Noninterest Income and Expenses - Summary of Noninterest Income and Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Noninterest income
Service charges on deposit accounts	$ 10,049	$ 9,669	$ 8,563
Trust fees	3,705	3,433	3,132
Mortgage banking fees	6,449	5,864	4,252
Brokerage commissions and fees	1,352	2,044	2,132
Marine finance fees	910	673	1,152
Interchange income	10,583	9,227	7,684
Other deposit based EFT fees	465	477	397
BOLI income	3,426	2,213	1,426
Gain on participated income	0	0	725
Other	6,291	3,827	2,555
Noninterest Income	43,230	37,427	32,018
Securities gains, net	86	368	161
Gain on sale of VISA stock	15,153	0	0
Bargain purchase gain, net	0	0	416
TOTAL	58,469	37,795	32,595
Noninterest expense
Salaries and wages	65,692	54,096	41,075
Employee benefits	11,732	9,903	9,564
Outsourced data processing costs	14,116	13,516	10,150
Telephone/data lines	2,291	2,108	1,797
Occupancy	13,290	13,122	8,744
Furniture and equipment	6,067	4,720	3,434
Marketing	4,784	3,633	4,428
Legal and professional fees	11,022	9,596	8,022
FDIC assessments	2,326	2,365	2,212
Amortization of intangibles	3,361	2,486	1,424
Asset dispositions expense	411	553	472
Net (gain)/loss on other real estate owned and repossessed assets	(711)	(509)	239
Early redemption cost for Federal Home Loan Bank advances	0	1,777	0
Other	15,535	13,515	12,209
TOTAL	$ 149,916	$ 130,881	$ 103,770