Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($)	Sep. 30, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Debt securities held to maturity, fair value	$ 413,820,000	$ 287,904,000
Preferred stock, par value (in dollars per share)	$ 1
Preferred stock authorized (in shares)	10,000,000
Preferred stock liquidation preference (in dollars per share)	$ 25,000
Preferred stock issued (in shares)	4,000	0
Preferred stock outstanding (in shares)	4,000	0
Common stock, par value (in dollars per share)	$ 1	$ 1
Common stock authorized (in shares)	150,000,000	150,000,000
Common stock issued (in shares)	86,611,114	79,013,729
Common stock outstanding (in shares)	86,611,114	79,013,729
Common stock issuable (in shares)	590,521	664,640