Investments - Unrealized net capital gains and losses (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Fair value
Fixed income securities	$ 23,261	$ 24,222
Equity securities (1)	1,614	1,511
Short-term investments	725	566
Derivative instruments	2	5
Gross unrealized Gains
Fixed income securities	1,355	1,310
Equity securities (1)	311	117
Short-term investments	0	0
Derivative instruments	2	5
Gross unrealized Losses
Fixed income securities	(98)	(200)
Equity securities (1)	(3)	(35)
Short-term investments	0	0
Derivative instruments	0	0
Unrealized net gains (losses)
Fixed income securities	1,257	1,110
Equity securities	308	82
Short-term investments	0	0
Derivative instruments	2	5
EMA limited partnerships	1	(2)
Unrealized net capital gains and losses, pre-tax	1,568	1,195
Amounts recognized for:
Amounts recognized for:	(315)	0
DAC and DSI	(189)	(140)
Amounts recognized	(504)	(140)
Deferred income taxes	(229)	(374)
Total unrealized net capital gains and losses	835	681
Fair value of derivative securities classified as assets, with unrealized net gains (losses) in AOCI		$ 5
Fair value of derivative liabilities with unrealized net capital gain (loss)	$ 2