Loans and the Allowance for Loan Losses (Details) - Aging analysis - USD ($) $ in Thousands	Jun. 30, 2019	Dec. 31, 2018
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 49,917	$ 51,855
Total Past Due and Nonaccrual	62,470	69,811
Current	5,032,278	4,475,088
Gross Loans	5,094,748	4,544,899
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	28,433	29,340
Total Past Due and Nonaccrual	35,604	32,660
Current	1,016,955	956,098
Gross Loans	1,052,559	988,758
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	12,686	15,135
Total Past Due and Nonaccrual	13,834	23,137
Current	3,097,440	2,755,030
Gross Loans	3,111,274	2,778,167
Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	3,579	2,934
Total Past Due and Nonaccrual	7,109	5,994
Current	595,104	459,395
Gross Loans	602,213	465,389
Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	5,219	4,446
Total Past Due and Nonaccrual	5,900	8,020
Current	320,761	301,971
Gross Loans	326,661	309,991
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual
Total Past Due and Nonaccrual	23
Current	2,018	2,594
Gross Loans	2,041	2,594
30 - 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	1,814	13,786
30 - 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	1,130	1,673
30 - 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		6,162
30 - 59 Days Past Due [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		2,496
30 - 59 Days Past Due [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	681	3,455
30 - 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	3
60 - 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	7,733	2,523
60 - 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	3,035
60 - 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	1,148	1,840
60 - 89 Days Past Due [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	3,530	564
60 - 89 Days Past Due [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		119
60 - 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	20
90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	3,006	1,647
90 Days or Greater Past Due and Still Accruing [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	3,006	1,647
90 Days or Greater Past Due and Still Accruing [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual
90 Days or Greater Past Due and Still Accruing [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual
90 Days or Greater Past Due and Still Accruing [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual
90 Days or Greater Past Due and Still Accruing [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual