Loans and the Allowance for Loan Losses (Details) - Credit quality indicators - USD ($) $ in Thousands	Sep. 30, 2019	Dec. 31, 2018
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	$ 5,115,473	$ 4,544,899
Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,113,743	988,758
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	3,030,816	2,778,167
Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	646,172	465,389
Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	322,307	309,991
Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,435	2,594
Pass [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	4,998,403	4,456,187
Pass [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,040,210	951,610
Pass [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	3,007,226	2,742,989
Pass [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	629,778	453,598
Pass [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	318,754	305,414
Pass [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	2,434	2,576
Special Mention [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	31,555	21,460
Special Mention [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	23,219	3,371
Special Mention [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	6,418	12,574
Special Mention [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1,918	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	85,515	67,252
Substandard [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	50,314	33,777
Substandard [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	17,172	22,604
Substandard [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	14,475	6,276
Substandard [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	3,553	4,577
Substandard [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Credit Quality Indicator [Line Items]
Gross loans	1	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