Fair Value Measurements - Fair Value Option (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Fair Value Inputs and Valuation Techniques
Fixed maturities, at fair value using the fair value option	$ 39		$ 39		$ 22
Changes in fair value of assets using fair value option	0	$ 0	0	$ 0
Real Estate Sector [Member]
Fair Value Inputs and Valuation Techniques
Fixed maturities, at fair value using the fair value option	$ 39		$ 39		$ 22