Loans and the Allowance for Loan Losses (Details) - Allowance for loan and lease losses - USD ($) $ in Thousands	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017
ALLL
ALLL, Individually evaluated for impairment	$ 213		$ 36
ALLL, Collectively evaluated for impairment	36,285		33,718
ALLL, Acquired portfolio	1,200		1,200
ALLL, Acquired with deteriorated credit quality
Total	37,698	$ 36,858	34,954	$ 33,594	$ 32,529	$ 31,748
Gross loans
Loans Receivable, Individually evaluated for impairment	62,483		59,932
Loans Receivable, Collectively evaluated for impairment	4,428,148		4,171,343
Loans Receivable, Acquired portfolio	597,413		311,115
Loans Receivables, Acquired with deteriorated credit quality	6,704		2,509
Total	5,094,748		4,544,899
Commercial Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	8,521		9,675
ALLL, Acquired portfolio	200		200
ALLL, Acquired with deteriorated credit quality
Total	8,721	8,660	9,875	8,960	8,550	8,233
Gross loans
Loans Receivable, Individually evaluated for impairment	32,559		29,896
Loans Receivable, Collectively evaluated for impairment	901,858		949,129
Loans Receivable, Acquired portfolio	112,743		7,224
Loans Receivables, Acquired with deteriorated credit quality	5,399		2,509
Total	1,052,559		988,758
Commercial Real Estate Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment	29		7
ALLL, Collectively evaluated for impairment	20,456		17,840
ALLL, Acquired portfolio	1,000		1,000
ALLL, Acquired with deteriorated credit quality
Total	21,485	21,561	18,847	18,221	17,435	17,112
Gross loans
Loans Receivable, Individually evaluated for impairment	17,555		18,327
Loans Receivable, Collectively evaluated for impairment	2,694,372		2,500,132
Loans Receivable, Acquired portfolio	398,042		259,708
Loans Receivables, Acquired with deteriorated credit quality	1,305
Total	3,111,274		2,778,167
Commercial Construction Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment	162
ALLL, Collectively evaluated for impairment	5,380		4,519
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	5,542	4,982	4,519	4,812	4,772	4,747
Gross loans
Loans Receivable, Individually evaluated for impairment	8,941		9,240
Loans Receivable, Collectively evaluated for impairment	552,712		456,149
Loans Receivable, Acquired portfolio	40,560
Loans Receivables, Acquired with deteriorated credit quality
Total	602,213		465,389
Residential Real Estate Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment	22		29
ALLL, Collectively evaluated for impairment	1,186		1,237
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	1,208	1,166	1,266	1,167	1,109	1,050
Gross loans
Loans Receivable, Individually evaluated for impairment	3,428		2,469
Loans Receivable, Collectively evaluated for impairment	277,490		263,449
Loans Receivable, Acquired portfolio	45,743		44,073
Loans Receivables, Acquired with deteriorated credit quality
Total	326,661		309,991
Consumer Portfolio Segment [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	2		2
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	2	1	2	3	2	1
Gross loans
Loans Receivable, Individually evaluated for impairment
Loans Receivable, Collectively evaluated for impairment	1,716		2,484
Loans Receivable, Acquired portfolio	325		110
Loans Receivables, Acquired with deteriorated credit quality
Total	2,041		2,594
Unallocated [Member]
ALLL
ALLL, Individually evaluated for impairment
ALLL, Collectively evaluated for impairment	740		445
ALLL, Acquired portfolio
ALLL, Acquired with deteriorated credit quality
Total	$ 740	$ 488	$ 445	$ 431	$ 661	$ 605