Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2019	Dec. 31, 2018
Available-for-sale securities, at fair value:
Fixed maturity securities (amortized cost)	$ 91,190	$ 92,429
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)	200,775,731	205,862,760
Common stock - shares outstanding (in shares)	200,775,731	205,862,760