Supplemental Cash Flow Information - Net change (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Supplemental Cash Flow Information [Abstract]
Transfer from Investments	$ 7	$ 2
Net change in proceeds managed
Net change in fixed income securities	15	(36)
Net change in short-term investments	66	11
Operating cash flow provided (used)	81	(25)
Net change in liabilities
Liabilities for collateral, beginning of period	(542)	(550)
Liabilities for collateral, end of period	(461)	(575)
Operating cash flow (used) provided	$ (81)	$ 25