Loans and the Allowance for Loan Losses (Details) - Allowance for loan and lease losses - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2017
ALLL
ALLL, Individually evaluated for impairment	$ 1,060	$ 36
ALLL, Collectively evaluated for impairment	34,598	33,718
ALLL, Acquired portfolio	1,200	1,200
ALLL, Acquired with deteriorated credit quality
Total	36,858	34,954	$ 32,529	$ 31,748
Gross loans
Loans Receivable, Individually evaluated for impairment	52,745	59,932
Loans Receivable, Collectively evaluated for impairment	4,267,369	4,171,343
Loans Receivable, Acquired portfolio	647,702	311,115
Loans Receivables, Acquired with deteriorated credit quality	8,989	2,509
Total	4,976,805	4,544,899
Commercial Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	8,460	9,675
ALLL, Acquired portfolio	200	200
ALLL, Acquired with deteriorated credit quality
Total	8,660	9,875	8,550	8,233
Gross loans
Loans Receivable, Individually evaluated for impairment	28,870	29,896
Loans Receivable, Collectively evaluated for impairment	893,678	949,129
Loans Receivable, Acquired portfolio	122,492	7,224
Loans Receivables, Acquired with deteriorated credit quality	6,159	2,509
Total	1,051,199	988,758
Commercial Real Estate Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment	1,035	7
ALLL, Collectively evaluated for impairment	19,526	17,840
ALLL, Acquired portfolio	1,000	1,000
ALLL, Acquired with deteriorated credit quality
Total	21,561	18,847	17,435	17,111
Gross loans
Loans Receivable, Individually evaluated for impairment	15,108	18,327
Loans Receivable, Collectively evaluated for impairment	2,603,459	2,500,132
Loans Receivable, Acquired portfolio	434,448	259,708
Loans Receivables, Acquired with deteriorated credit quality	1,181
Total	3,054,196	2,778,167
Commercial Construction Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	4,982	4,519
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	4,982	4,519	4,772	4,747
Gross loans
Loans Receivable, Individually evaluated for impairment	6,326	9,240
Loans Receivable, Collectively evaluated for impairment	498,503	456,149
Loans Receivable, Acquired portfolio	41,561
Loans Receivables, Acquired with deteriorated credit quality	1,649
Total	548,039	465,389
Residential Real Estate Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment	25	29
ALLL, Collectively evaluated for impairment	1,141	1,237
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	1,166	1,266	1,109	1,051
Gross loans
Loans Receivable, Individually evaluated for impairment	2,441	2,469
Loans Receivable, Collectively evaluated for impairment	267,903	263,449
Loans Receivable, Acquired portfolio	48,871	44,073
Loans Receivables, Acquired with deteriorated credit quality
Total	319,215	309,991
Consumer Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	1	2
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	1	2	2	1
Gross loans
Loans Receivable, Individually evaluated for impairment
Loans Receivable, Collectively evaluated for impairment	3,826	2,484
Loans Receivable, Acquired portfolio	330	110
Loans Receivables, Acquired with deteriorated credit quality
Total	4,156	2,594
Unallocated [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	488	445
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	$ 488	$ 445	$ 661	$ 605