Condensed Consolidated Statements of Financial Position (unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2024	Dec. 31, 2023
Statement of Financial Position [Abstract]
Fixed income securities, at fair value, amortized cost	$ 53,447	$ 49,649
Equity securities, at fair value, cost	1,829	2,244
Short-term, at fair value, amortized cost	$ 6,995	$ 5,145
Preferred stock, par value (in dollars per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	82,000	82,000
Preferred stock, shares outstanding (in shares)	82,000	82,000
Preferred stock, value aggregate liquidation preference	$ 2,050	$ 2,050
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	2,000,000,000.0	2,000,000,000.0
Common stock, shares issued (in shares)	900,000,000	900,000,000
Common stock, shares outstanding (in shares)	265,000,000	262,000,000
Treasury stock, shares (in shares)	635,000,000	638,000,000