Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Thousands	Sep. 30, 2021	Dec. 31, 2020
Pledged securities that can be sold or repledged	$ 118,178	$ 105,136
Investment securities, available for sale, amortized cost	3,473,923	4,621,027
Investment securities, held to maturity, fair value	2,413,938	1,842,281
Equity and other securities, cost	$ 467,349	$ 449,008
Preferred stock, par value	$ 1.00	$ 1.00
Preferred stock, shares authorized	1,000,000	1,000,000
Common stock, par value	$ 0.50	$ 0.50
Common stock, shares authorized	250,000,000	250,000,000
Common stock, shares issued	159,741,898	159,741,898
Common stock issuable, shares	15,683	18,113
Treasury stock, common shares	31,058,333	31,426,742
Series A Series C Series And E Preferred Stock [Member]
Preferred stock, shares issued	350,000	350,000
Preferred stock, shares outstanding	350,000	350,000
Preferred stock, liquidation preference per share	$ 1,000	$ 1,000
Series F And Series G Preferred Stock [Member]
Preferred stock, shares issued	140,000	90,000
Preferred stock, shares outstanding	140,000	90,000
Preferred stock, liquidation preference per share	$ 10,000	$ 10,000