Supplemental Cash Flow Information - Net change (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Net change in proceeds managed
Net change in fixed income securities	$ 68	$ 9
Net change in short-term investments	(37)	12
Operating cash flow provided	31	21
Net change in liabilities
Liabilities for collateral, beginning of period	(542)	(550)
Liabilities for collateral, end of period	(511)	(529)
Operating cash flow used	$ (31)	$ (21)