Condensed Consolidated Balance Sheets Parenthetical - USD ($) $ in Millions	Sep. 30, 2018	Dec. 31, 2017
Statement of Financial Position [Abstract]
Fixed maturities, amortized cost	$ 22,313	$ 21,774
Equity securities, cost	48	45
Mortgage loans on real estate valuation allowance	1	1
Securities pledged, amortized costs	$ 938	$ 864
Common stock, par value	$ 50	$ 50
Common stock, shares authorized	100,000	100,000
Common stock, shares issued	55,000	55,000
Common stock, shares outstanding	55,000	55,000