Loans Receivable, Net - Components of Loans Receivable, Net (Details) - USD ($) $ in Thousands	Jun. 30, 2021	Mar. 31, 2021	Dec. 31, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 7,820,790		$ 7,756,106
Deferred origination costs, net	7,437		9,486
Allowance for loan credit losses	(53,876)	$ (59,976)	(60,735)	$ (38,509)	$ (29,635)	$ (16,852)
Total loans receivable, net	7,774,351		7,704,857
Commercial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	5,356,663		5,107,185
Commercial | Commercial and industrial
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	474,919		470,656
Commercial | Commercial and industrial | Paycheck Protection Program
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	83,000		95,400
Commercial | Commercial real estate – owner occupied
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	1,045,514		1,145,065
Commercial | Commercial real estate – investor
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	3,836,230		3,491,464
Consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,464,127		2,648,921
Allowance for loan credit losses	(1,267)	$ (1,406)	(1,770)	$ (4,220)	$ (4,314)	$ (591)
Consumer | Residential real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	2,168,545		2,309,459
Consumer | Home equity loans and lines
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	255,097		285,016
Consumer | Other consumer
Financing Receivable, Allowance for Credit Loss [Line Items]
Total loans receivable	$ 40,485		$ 54,446