CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
ASSETS
Debt Securities, Available-for-sale, Amortized Cost	$ 3,443,516	$ 2,256,189
Allowance for Credit Losses	(104)	94
Securities—held-to-maturity, fair value	$ 466,002	$ 448,681
SHAREHOLDERS’ EQUITY
Preferred Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Preferred Stock, Shares Authorized	500,000	500,000
Preferred Stock, Shares Outstanding	0	0
Voting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	50,000,000	50,000,000
Common Stock, Shares, Issued	34,251,991	35,159,200
Common Stock, Shares, Outstanding	34,251,991	35,159,200
Nonvoting Common Stock [Member]
SHAREHOLDERS’ EQUITY
Common Stock, Par or Stated Value Per Share	$ 0.01	$ 0.01
Common Stock, Shares Authorized	5,000,000	5,000,000
Common Stock, Shares, Issued	0	0
Common Stock, Shares, Outstanding	0	0
Loans [Member] | Recurring [Member]
ASSETS
Loans Held-for-sale, Fair Value Disclosure	$ 41,480	$ 133,554