Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2017	Dec. 31, 2016
Available-for-sale securities, at fair value:
Fixed maturity securities (amortized cost)	$ 86,194	$ 84,287
Variable interest entities' fixed maturity securities (amortized cost)	0	200
Equity securities (cost)	$ 262	$ 260
Stockholders' Equity
Preferred stock - shares authorized (in shares)	10,000,000	10,000,000
Common stock - shares authorized (in shares)	800,000,000	800,000,000
Common stock - shares issued (in shares)	222,237,262	226,335,105
Common stock - shares outstanding (in shares)	222,237,262	226,335,105