Investments - Unrealized Net Capital Gains and Losses (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Fair value
Fixed income securities	$ 21,567	$ 23,261
Equity securities	1,705	1,614
Short-term investments	1,066	725
Derivative instruments		2
Gross unrealized Gains
Fixed income securities	843	1,355
Equity securities		311
Short-term investments	0	0
Derivative instruments		2
Gross unrealized Losses
Fixed income securities	(317)	(98)
Equity securities		(3)
Short-term investments	0	0
Derivative instruments		0
Unrealized net gains (losses)
Fixed income securities	526	1,257
Equity securities		308
Short-term investments	0	0
Derivative instruments		2
EMA limited partnerships	1	1
Unrealized net capital gains and losses, pre-tax	527	1,568
Amount recognized for:
Insurance reserves	0	(315)
DAC and DSI	(70)	(189)
Amounts recognized	(70)	(504)
Deferred income taxes	(96)	(229)
Total unrealized net capital gains and losses	$ 361	835
Fair value of derivative securities classified as liabilities, with unrealized net gains (losses) in AOCI		$ 2