Loans and the Allowance for Loan Losses (Details) - Credit quality indicators - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 5,094,748	$ 4,544,899
Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,052,559	988,758
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	3,111,274	2,778,167
Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	602,213	465,389
Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	326,661	309,991
Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,041	2,594
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	4,994,032	4,456,187
Pass [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	997,503	951,610
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	3,084,014	2,742,989
Pass [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	589,165	453,598
Pass [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	321,316	305,414
Pass [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,034	2,576
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	30,997	21,460
Special Mention [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	19,269	3,371
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	7,622	12,574
Special Mention [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	4,106	5,515
Special Mention [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Special Mention [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Substandard [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	69,719	67,252
Substandard [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	35,787	33,777
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	19,638	22,604
Substandard [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	8,942	6,276
Substandard [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	5,345	4,577
Substandard [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	7	18
Doubtful [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Doubtful [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Doubtful [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Doubtful [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Doubtful [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans
Doubtful [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans