Consolidated Balance Sheet Parentheticals (Unaudited at March 31, 2019) - USD ($) $ in Millions	Mar. 31, 2019	Dec. 31, 2018
Statement of Financial Position [Abstract]
Fixed maturities, available for sale, amortized cost	$ 64,216	$ 63,601
Equity securities, cost	$ 375	$ 382
Common stock, shares authorized (in shares)	1,750,000,000	1,750,000,000.0
Common stock, shares issued (in shares)	262,000,000	263,700,000
Common stock, shares outstanding (in shares)	261,900,000	263,600,000
Treasury stock, at cost (in shares)	514,200,000	510,900,000