Consolidated Statements of Condition (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Statement Of Financial Position [Abstract]
Held-to-Maturity: Fair Value	$ 3,477,346	$ 3,348,693
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)	58,553,365	58,285,624
Common Stock, outstanding (in shares)	40,394,234	40,119,312
Treasury Stock (in shares)	18,159,131	18,166,312