Supplemental Cash Flow Information - Net change (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Net change in proceeds managed
Net change in fixed income securities	$ 28	$ 15
Net change in short-term investments	(90)	66
Operating cash flow (used) provided	(62)	81
Net change in liabilities
Liabilities for collateral, beginning of period	(525)	(542)
Liabilities for collateral, end of period	(587)	(461)
Operating cash flow provided (used)	$ 62	$ (81)