Loans Receivable, Net - Components of Loans Receivable, Net (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 7,872,537	$ 7,756,106
Deferred origination costs, net	8,029	9,486
Allowance for loan credit losses	(59,976)	(60,735)	$ (29,635)	$ (16,852)
Total loans receivable, net	7,820,590	7,704,857
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	5,368,947	5,107,185
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	498,245	470,656
Commercial | Commercial and industrial | Paycheck Protection Program
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	109,700	95,400
Commercial | Commercial real estate – owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	1,066,351	1,145,065
Commercial | Commercial real estate – investor
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	3,804,351	3,491,464
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,503,590	2,648,921
Allowance for loan credit losses	(1,406)	(1,770)	$ (4,314)	$ (591)
Consumer | Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,189,348	2,309,459
Consumer | Home equity loans and lines
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	267,591	285,016
Consumer | Other consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 46,651	$ 54,446