Investments (Components of Net Investment Gains Losses) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Marketable Securities, Gain (Loss) [Abstract]
Fixed maturity securities — net gains (losses) on sales and disposals	$ 45	$ 165	$ 5	$ 263
Equity securities — net gains (losses) on sales and disposals	7	13	50	19
Other net investment gains (losses):
Mortgage loans	(16)	(98)	(31)	(162)
Real estate and real estate joint ventures	271	45	270	47
Other limited partnership interests	(12)	(14)	(29)	(41)
Other	(69)	(57)	(127)	(75)
Subtotal	218	24	122	(108)
FVO CSEs - changes in estimated fair value subsequent to consolidation:
Commercial mortgage loans	0	(1)	(1)	0
Securities	0	0	0	1
Long-term debt — related to commercial mortgage loans	(1)	0	0	0
Non-investment portfolio gains (losses)	(113)	243	(9)	388
Subtotal	(114)	242	(10)	389
Total net investment gains (losses)	104	266	112	281
Fixed Maturity Securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(3)	(14)	(3)	(92)
Net investment gains (losses)	42	151	2	171
Industrial
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(8)	0	(79)
Communications
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	0	0	(3)
U.S. corporate and foreign corporate securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(8)	0	(82)
RMBS
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	(4)	0	(8)
Equity securities
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(5)	(16)	(13)	(67)
Net investment gains (losses)	2	(3)	37	(48)
Nonredeemable Preferred Stock [Member]
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	0	0	(1)	0
Common Stock
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	(5)	(16)	(12)	(67)
ABS
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings	$ 0	$ (2)	0	(2)
State and political subdivision
Marketable Securities, Gain (Loss) [Abstract]
Total OTTI losses recognized in earnings			$ (3)	$ 0