Consolidated Balance Sheet (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Statement of Financial Position [Abstract]
Fixed maturities, available for sale at amortized cost	$ 35,445	$ 33,735
Equity securities, available for sale at cost	$ 1,356	$ 1,351
Common Stock, par value (USD per share)	$ 0	$ 0
Common Stock, shares authorized	200,000,000	200,000,000
Common Stock, shares outstanding	87,591,671	86,924,399