Consolidated Statements Of Condition (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020	Sep. 30, 2020
Held-to-maturity securities, allowance for credit loss	$ 83	$ 59	$ 63
Held-to-maturity securities, fair value	$ 2,699,480	$ 593,767	$ 575,947
Preferred stock, authorized (in shares)	20,000,000	20,000,000	20,000,000
Common stock, stated value (usd per share)	$ 1.00	$ 1.00	$ 1.00
Common stock, authorized (in shares)	100,000,000	100,000,000	100,000,000
Common stock, issued (in shares)	58,793,715	58,473,252	58,322,775
Treasury stock (in shares)	1,837,689	1,703,627	720,784
Series D Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25	$ 25	$ 25
Preferred stock, issued (in shares)	5,000,000	5,000,000	5,000,000
Preferred stock, outstanding (in shares)	5,000,000	5,000,000	5,000,000
Series E Preferred Stock
Preferred stock, liquidation value per share (usd per share)	$ 25,000	$ 25,000	$ 25,000
Preferred stock, issued (in shares)	11,500	11,500	11,500
Preferred stock, outstanding (in shares)	11,500	11,500	11,500