Investments - Unrealized Net Capital Gains and Losses (Details) - USD ($) $ in Millions	Mar. 31, 2018	Dec. 31, 2017
Fair value
Fixed income securities	$ 22,401	$ 23,261
Equity securities	1,503	1,614
Short-term investments	596	725
Derivative instruments	2	2
Gross unrealized Gains
Fixed income securities	1,008	1,355
Equity securities		311
Short-term investments	0	0
Derivative instruments	2	2
Gross unrealized Losses
Fixed income securities	(252)	(98)
Equity securities		(3)
Short-term investments	0	0
Derivative instruments	0	0
Unrealized net gains (losses)
Fixed income securities	756	1,257
Equity securities		308
Short-term investments	0	0
Derivative instruments	2	2
Equity method ("EMA") limited partnerships	1	1
Unrealized net capital gains and losses, pre-tax	759	1,568
Amount recognized for:
Insurance reserves	(119)	(315)
DAC and DSI	(106)	(189)
Amounts recognized	(225)	(504)
Deferred income taxes	(112)	(229)
Total unrealized net capital gains and losses	422	835
Fair value of derivative securities classified as liabilities, with unrealized net gains (losses) in AOCI	$ 2	$ 2