Schedule II-Condensed Financial Information Of Registrant (Balance Sheets (Parenthetical)) (Details) - USD ($) $ / shares in Units, $ in Millions	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale fixed maturity securities investments, current, amortized cost	$ 19,021	$ 16,894
Available-for-sale fixed maturity securities investments, long-term, amortized cost	$ 487	$ 486
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	252,922,161	257,395,577
Common stock, shares outstanding	252,922,161	257,395,577
Parent Company [Member]
Available-for-sale fixed maturity securities investments, current, amortized cost	$ 592	$ 589
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.01	$ 0.01
Common stock, shares authorized	900,000,000	900,000,000
Common stock, shares issued	252,922,161	257,395,577
Common stock, shares outstanding	252,922,161	257,395,577