Loans Receivable, Net - Components of Loans Receivable, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 7,756,106	$ 6,214,652
Deferred origination costs, net of fees	9,486	9,880
Allowance for credit losses	(60,735)	(16,852)	$ (16,577)
Total loans receivable, net	7,704,857	6,207,680
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	5,107,185	3,485,497
Commercial | Commercial real estate – owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	470,656	396,434
Commercial | Commercial real estate – owner occupied | Paycheck Protection Program
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	95,400
Commercial | Commercial real estate – owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	1,145,065	792,653
Commercial | Commercial real estate - investor
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	3,491,464	2,296,410
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,648,921	2,729,155
Allowance for credit losses	(1,770)	(591)	$ (486)
Consumer | Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,309,459	2,321,157
Consumer | Home equity loans and lines
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	285,016	318,576
Consumer | Other consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 54,446	$ 89,422