Fair Value of Assets and Liabilities (Level 3 Assets and Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	$ 708	$ 815	$ 720	$ 1,059
Total gains (losses) included in: Net income	5	11	4	13
Total gains (losses) included in: OCI	3	(11)	14	(17)
Transfers into Level 3	0	15	34	23
Transfers out of Level 3	(217)	(23)	(290)	(177)
Purchases	33	47	108	74
Sales	(6)	(25)	(27)	(75)
Issues	0	0	0	0
Settlements	(26)	(17)	(63)	(88)
Balance at end of period	500	812	500	812
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	(304)	(315)	(299)	(323)
Total gains (losses) included in: net income	2	(19)	10	(24)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(1)	0	(2)	(1)
Settlements	1	1	5	5
Balance at end of period	(306)	(295)	(306)	(295)
Fixed income securities
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	662	775	666	1,028
Total gains (losses) included in: Net income	1	12	16	13
Total gains (losses) included in: OCI	3	(10)	11	(17)
Transfers into Level 3	0	15	34	23
Transfers out of Level 3	(217)	(23)	(290)	(177)
Purchases	11	28	81	47
Sales	(6)	(25)	(27)	(75)
Issues	0	0	0	0
Settlements	(26)	(17)	(63)	(87)
Balance at end of period	428	755	428	755
Municipal
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	70	101	78	106
Total gains (losses) included in: Net income	1	2	12	3
Total gains (losses) included in: OCI	(1)	0	(6)	(2)
Transfers into Level 3	0	0	6	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	(4)	(14)	(24)	(17)
Issues	0	0	0	0
Settlements	0	0	0	(1)
Balance at end of period	66	89	66	89
Corporate - public
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	41		44
Total gains (losses) included in: Net income	0		0
Total gains (losses) included in: OCI	0		1
Transfers into Level 3	0		1
Transfers out of Level 3	(6)		(13)
Purchases	3		6
Sales	(2)		(2)
Issues	0		0
Settlements	0		(1)
Balance at end of period	36		36
Corporate - privately placed
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	474		447
Total gains (losses) included in: Net income	0		4
Total gains (losses) included in: OCI	2		14
Transfers into Level 3	0		16
Transfers out of Level 3	(211)		(276)
Purchases	1		68
Sales	0		0
Issues	0		0
Settlements	(24)		(31)
Balance at end of period	242		242
Corporate
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period		569		792
Total gains (losses) included in: Net income		10		11
Total gains (losses) included in: OCI		(9)		(15)
Transfers into Level 3		0		2
Transfers out of Level 3		(23)		(150)
Purchases		1		20
Sales		(11)		(58)
Issues		0		0
Settlements		(2)		(67)
Balance at end of period		535		535
ABS
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period		105		129
Total gains (losses) included in: Net income		0		(1)
Total gains (losses) included in: OCI		(1)		1
Transfers into Level 3		15		21
Transfers out of Level 3		0		(27)
Purchases		27		27
Sales		0		0
Issues		0		0
Settlements		(15)		(19)
Balance at end of period		131		131
ABS - CDO
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	33		53
Total gains (losses) included in: Net income	0		0
Total gains (losses) included in: OCI	2		4
Transfers into Level 3	0		8
Transfers out of Level 3	0		(1)
Purchases	0		0
Sales	0		(1)
Issues	0		0
Settlements	(2)		(30)
Balance at end of period	33		33
ABS - consumer and other
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	44		44
Total gains (losses) included in: Net income	0		0
Total gains (losses) included in: OCI	0		(2)
Transfers into Level 3	0		3
Transfers out of Level 3	0		0
Purchases	7		7
Sales	0		0
Issues	0		0
Settlements	0		(1)
Balance at end of period	51		51
CMBS
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period				1
Total gains (losses) included in: Net income				0
Total gains (losses) included in: OCI				(1)
Transfers into Level 3				0
Transfers out of Level 3				0
Purchases				0
Sales				0
Issues				0
Settlements				0
Balance at end of period		0		0
Equity securities
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	52	46	60	37
Total gains (losses) included in: Net income	0	0	(16)	0
Total gains (losses) included in: OCI	0	(1)	3	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	22	19	27	27
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	74	64	74	64
Free-standing derivatives, net
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	(7)	(7)	(7)	(7)
Total gains (losses) included in: Net income	4	(1)	4	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	(1)
Balance at end of period	(3)	(8)	(3)	(8)
Other assets
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	1	1	1	1
Total gains (losses) included in: Net income	0	0	0	0
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	1	1	1	1
Contractholder funds: Derivatives embedded in life and annuity contracts
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	(304)	(315)	(299)	(323)
Total gains (losses) included in: net income	2	(19)	10	(24)
Total gains (losses) included in: OCI	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Issues	(1)	0	(2)	(1)
Settlements	1	1	5	5
Balance at end of period	(306)	(295)	(306)	(295)
Contract benefits
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Gains (losses) for Level 3 assets and liabilities still held at the balance sheet date	$ 3	$ (8)	$ 1	$ (8)