Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Supplemental Cash Flow Information [Abstract]
Non-cash modifications of certain mortgage loans, fixed income securities, limited partnerships and other investments, as well as mergers completed with equity securities	$ 16	$ 105
Liabilities assumed		34
Net change in proceeds managed
Net change in fixed income securities	38	(126)
Net change in short-term investments	(64)	175
Operating cash flow (used) provided	(26)	49
Net change in cash	1	0
Net change in proceeds managed	(25)	49
Net change in liabilities
Liabilities for collateral, beginning of period	(550)	(550)
Liabilities for collateral, end of period	(575)	(501)
Operating cash flow provided (used)	$ 25	$ (49)