Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Mar. 31, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
HTM debt securities	$ 2,042,912,000	$ 2,095,620,000
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock authorized (in shares)	10,000,000	10,000,000
Preferred stock issued (in shares)	3,662	3,662
Preferred stock outstanding (in shares)	3,662	3,662
Preferred stock liquidation preference (in dollars per share)	$ 25,000	$ 25,000
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock authorized (in shares)	200,000,000	200,000,000
Common stock issued (in shares)	119,136,518	119,010,319
Common stock outstanding (in shares)	119,136,518	119,010,319
Common stock issuable (in shares)	560,833	620,108