Consolidated Statements of Financial Position (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Amortized cost, net	$ 61,451	$ 56,293
Equity securities, at fair value, cost	3,853	6,568
Other short term Investments, amortized cost	$ 7,800	$ 4,256
Preferred stock, par or stated value per share (in USD per share)	$ 1	$ 1
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	81,000	92,500
Preferred stock, shares outstanding (in shares)	81,000.0	92,500
Preferred Stock, liquidation preference	$ 2,025	$ 2,313
Common stock, par or stated value per share (in USD 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)	304,000,000	319,000,000
Treasury stock, shares (in shares)	596,000,000	581,000,000