Condensed Consolidated Statements of Financial Position (unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Fixed income securities, at fair value, amortized cost (in dollars)	$ 38,811	$ 40,034
Equity securities, at fair value, cost (in dollars)	2,939	2,740
Short-term, at fair value, amortized cost (in dollars)	$ 6,428	$ 6,807
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)	81,000	81,000
Preferred stock, shares outstanding (in shares)	81,000	81,000
Preferred stock, shares aggregate liquidation preference (in shares)	$ 2,025	$ 2,025
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	2,000,000,000	2,000,000,000
Common stock, shares issued (in shares)	900,000,000	900,000,000
Common stock, shares outstanding (in shares)	288,000,000	304,000,000
Treasury stock, shares (in shares)	612,000,000	596,000,000