Consolidated Statements of Financial Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Interest-bearing deposits in other banks, collateral	$ 7,390	$ 0
Amortized cost of investment securities, available for sale	2,450,265	1,909,483
Allowance for credit losses on held-to-maturity debt securities	6
Investment securities, held-to-maturity-at cost, fair value	116,421	136,625
Allowance for credit loss	$ 228,804	$ 47,576
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)	57,575,783	57,435,658
Treasury stock (in shares)	9,819,627	5,868,772