Loans and the Allowance for Loan Losses (Details) - Composition of loan portfolio - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired [Line Items]
Gross loans	$ 4,544,899	$ 4,174,810
Net deferred (fees)	(3,807)	(3,354)
Total loans receivable	4,541,092	4,171,456
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Gross loans	988,758	824,082
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Gross loans	2,778,167	2,592,909
Construction Loans [Member]
Financing Receivable, Impaired [Line Items]
Gross loans	465,389	483,216
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Gross loans	309,991	271,795
Consumer Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Gross loans	$ 2,594	$ 2,808