CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($)	Sep. 30, 2023	Dec. 31, 2022
Statement of Financial Position [Abstract]
Securities, Available-for-Sale, at Fair Value, Amortized Cost	$ 1,891,435,000	$ 2,094,826,000
Securities, Available-for-Sale, at Fair Value, Allowance for Credit Losses	$ 0	$ 0
Common stock, stated value (in dollars per share)	$ 1	$ 1
Common stock, shares authorized (in shares)	45,000,000	45,000,000