CONSOLIDATED STATEMENTS OF FINANCIAL CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Interest-bearing deposits in banks and other financial institutions, collateral	$ 7,000	$ 7,390
Available-for-sale securities, amortized cost basis	3,000,986	2,450,265
Allowance for credit loss	5	6
Held-to-maturity securities, fair value	107,629	116,421
Allowance for credit losses	$ 204,818	$ 228,804
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	90,000,000	90,000,000
Common stock, issued (in shares)	57,589,330	57,575,783
Treasury stock, shares (in shares)	10,086,936	9,819,627