Consolidated Statements of Condition (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Statement Of Financial Position [Abstract]
Held-to-Maturity: Fair Value	$ 3,348,693	$ 3,062,882
Common Stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, authorized (in shares)	500,000,000	500,000,000
Common Stock, issued (in shares)	58,285,624	58,166,910
Common Stock, outstanding (in shares)	40,119,312	40,039,695
Treasury Stock (in shares)	18,166,312	18,127,215