Allowance for Loan Losses - Summary of Changes in the Allowance for Loan Losses, by Loan Portfolio Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	$ 29,831	$ 26,464	$ 25,450
Charge-offs	(9,079)	(9,016)	(6,174)
Recoveries	4,900	4,849	3,107
Net (charge-offs) / recoveries	(4,179)	(4,167)	(3,067)
Decrease in FDIC indemnification asset	(155)	(697)	(270)
Provision for loan losses	4,275	8,231	4,351
Ending balance	29,772	29,831	26,464
Commercial
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	9,331	8,582	10,152
Charge-offs	(2,824)	(2,349)	(1,275)
Recoveries	2,587	923	195
Net (charge-offs) / recoveries	(237)	(1,426)	(1,080)
Decrease in FDIC indemnification asset	(155)	331	(50)
Provision for loan losses	(1,093)	1,844	(440)
Ending balance	7,846	9,331	8,582
SBA
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	1,978	2,433	3,015
Charge-offs	(221)	(387)	(313)
Recoveries	61	82	227
Net (charge-offs) / recoveries	(160)	(305)	(86)
Decrease in FDIC indemnification asset	0	0	0
Provision for loan losses	150	(150)	(496)
Ending balance	1,968	1,978	2,433
Construction
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	2,176	1,711	1,486
Charge-offs	(13)	0	0
Recoveries	911	2,157	1,265
Net (charge-offs) / recoveries	898	2,157	1,265
Decrease in FDIC indemnification asset	0	(1,145)	(101)
Provision for loan losses	(678)	(547)	(939)
Ending balance	2,396	2,176	1,711
Consumer
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	9,812	8,668	6,591
Charge-offs	(5,978)	(5,233)	(4,399)
Recoveries	1,242	1,486	1,372
Net (charge-offs) / recoveries	(4,736)	(3,747)	(3,027)
Decrease in FDIC indemnification asset	0	93	36
Provision for loan losses	5,682	4,798	5,068
Ending balance	10,758	9,812	8,668
Mortgage
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	5,755	4,294	3,475
Charge-offs	(43)	(1,047)	(187)
Recoveries	99	201	48
Net (charge-offs) / recoveries	56	(846)	(139)
Decrease in FDIC indemnification asset	0	24	(155)
Provision for loan losses	117	2,283	1,113
Ending balance	5,928	5,755	4,294
Unallocated
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance	779	776	731
Charge-offs	0	0	0
Recoveries	0	0	0
Net (charge-offs) / recoveries	0	0	0
Decrease in FDIC indemnification asset	0	0	0
Provision for loan losses	97	3	45
Ending balance	$ 876	$ 779	$ 776