Loans and the Allowance for Credit Losses (Details) - Aging analysis - USD ($) $ in Thousands	Jun. 30, 2021	Dec. 31, 2020	Jun. 30, 2020
Financing Receivable, Past Due [Line Items]
Nonaccrual	$ 56,213	$ 61,696
Total Past Due and Nonaccrual	76,475	98,000
Gross Loans	6,421,598	6,247,681
Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	31,083	33,019	$ 31,083
Total Past Due and Nonaccrual	35,968	38,204
Gross Loans	1,402,697	1,521,967
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	16,005	10,111	16,005
Total Past Due and Nonaccrual	23,612	33,064
Gross Loans	4,138,518	3,783,550
Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	4,765	14,015	4,765
Total Past Due and Nonaccrual	7,986	16,487
Gross Loans	587,121	617,747
Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual	4,360	4,551	$ 4,360
Total Past Due and Nonaccrual	8,907	10,243
Gross Loans	286,907	322,564
Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Nonaccrual
Total Past Due and Nonaccrual	2	2
Gross Loans	6,355	1,853
Current [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	6,345,123	6,149,681
Current [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	1,366,729	1,483,763
Current [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	4,114,906	3,750,486
Current [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	579,135	601,260
Current [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	278,000	312,321
Current [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	6,353	1,851
30 - 59 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	509	18,544
30 - 59 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	297	1,445
30 - 59 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		13,258
30 - 59 Days Past Due [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		2,472
30 - 59 Days Past Due [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	210	1,367
30 - 59 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	2	2
60 - 89 Days Past Due [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	99	4,939
60 - 89 Days Past Due [Member] | Commercial Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		558
60 - 89 Days Past Due [Member] | Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual		4,140
60 - 89 Days Past Due [Member] | Commercial Construction Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual
60 - 89 Days Past Due [Member] | Residential Real Estate Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	99	241
60 - 89 Days Past Due [Member] | Consumer Portfolio Segment [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual
90 Days or Greater Past Due and Still Accruing [Member]
Financing Receivable, Past Due [Line Items]
Total Past Due and Nonaccrual	19,654	12,821
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	4,588	3,182
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	7,607	5,555
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	3,221
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	4,238	4,084
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