Supplemental Cash Flow Information (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2017	Jun. 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	$ 4	$ 99
Liabilities assumed		34
Net change in proceeds managed
Net change in fixed income securities	9	0
Net change in short-term investments	12	(45)
Operating cash flow provided (used)	21	(45)
Net change in liabilities
Liabilities for collateral, beginning of period	(550)	(550)
Liabilities for collateral, end of period	(529)	(595)
Operating cash flow (used) provided	$ (21)	$ 45