CONSOLIDATED STATEMENTS OF CONDITION (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Dec. 31, 2022
Assets:
Available-for-sale investment securities, pledged amount	$ 640,396	$ 466,902
Amortized Cost	3,871,881	4,675,474
Held-to-maturity securities, fair value	1,083,330	1,034,795
Equity and other securities, cost	$ 53,595	$ 82,424
Shareholders' equity:
Preferred stock, par value (in dollars per share)	$ 1.00	$ 1.00
Preferred stock, shares authorized	500,000	500,000
Preferred stock, shares issued	0	0
Common stock, par value (in dollars per share)	$ 1.00	$ 1.00
Common stock, shares authorized	75,000,000	75,000,000
Common stock, shares issued	54,359,535	54,190,201
Treasury stock, shares at cost	634,618	452,952
Shares held by deferred compensation arrangements	117,103	135,437