Fair Value of Assets and Liabilities (Level 3 Assets and Liabilities) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	$ 743	$ 989	$ 720	$ 1,059
Total gains (losses) included in: Net income	0	4	(1)	2
Total gains (losses) included in: OCI	13	3	11	(6)
Transfers into Level 3	31	0	34	8
Transfers out of Level 3	(61)	(133)	(73)	(154)
Purchases	15	6	75	27
Sales	(5)	(2)	(21)	(50)
Issues	0	0	0	0
Settlements	(28)	(52)	(37)	(71)
Balance at end of period	708	815	708	815
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance at beginning of period	(313)	(326)	(299)	(323)
Total gains (losses) included in: net income	7	9	(8)	5
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	(1)	(1)
Settlements	2	2	4	4
Balance at end of period	(304)	(315)	(304)	(315)
Fixed income securities
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	694	956	666	1,028
Total gains (losses) included in: Net income	3	3	15	1
Total gains (losses) included in: OCI	13	2	8	(7)
Transfers into Level 3	31	0	34	8
Transfers out of Level 3	(61)	(133)	(73)	(154)
Purchases	15	0	70	19
Sales	(5)	(2)	(21)	(50)
Issues	0	0	0	0
Settlements	(28)	(51)	(37)	(70)
Balance at end of period	662	775	662	775
Municipal
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	66	106	78	106
Total gains (losses) included in: Net income	0	1	11	1
Total gains (losses) included in: OCI	3	(3)	(5)	(2)
Transfers into Level 3	6	0	6	0
Transfers out of Level 3	0	0	0	0
Purchases	0	0	0	0
Sales	(5)	(2)	(20)	(3)
Issues	0	0	0	0
Settlements	0	(1)	0	(1)
Balance at end of period	70	101	70	101
Corporate - public
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	38		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	0		(7)
Purchases	3		3
Sales	0		0
Issues	0		0
Settlements	0		(1)
Balance at end of period	41		41
Corporate - privately placed
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	497		447
Total gains (losses) included in: Net income	3		4
Total gains (losses) included in: OCI	8		12
Transfers into Level 3	16		16
Transfers out of Level 3	(60)		(65)
Purchases	12		67
Sales	0		0
Issues	0		0
Settlements	(2)		(7)
Balance at end of period	474		474
Corporate
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period		739		792
Total gains (losses) included in: Net income		3		1
Total gains (losses) included in: OCI		3		(6)
Transfers into Level 3		0		2
Transfers out of Level 3		(127)		(127)
Purchases		0		19
Sales		0		(47)
Issues		0		0
Settlements		(49)		(65)
Balance at end of period		569		569
ABS
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period		111		129
Total gains (losses) included in: Net income		(1)		(1)
Total gains (losses) included in: OCI		2		2
Transfers into Level 3		0		6
Transfers out of Level 3		(6)		(27)
Purchases		0		0
Sales		0		0
Issues		0		0
Settlements		(1)		(4)
Balance at end of period		105		105
ABS - CDO
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	50		53
Total gains (losses) included in: Net income	0		0
Total gains (losses) included in: OCI	3		2
Transfers into Level 3	6		8
Transfers out of Level 3	(1)		(1)
Purchases	0		0
Sales	0		(1)
Issues	0		0
Settlements	(25)		(28)
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	43		44
Total gains (losses) included in: Net income	0		0
Total gains (losses) included in: OCI	(1)		(2)
Transfers into Level 3	3		3
Transfers out of Level 3	0		0
Purchases	0		0
Sales	0		0
Issues	0		0
Settlements	(1)		(1)
Balance at end of period	44		44
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	56	39	60	37
Total gains (losses) included in: Net income	(4)	0	(16)	0
Total gains (losses) included in: OCI	0	1	3	1
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Purchases	0	6	5	8
Sales	0	0	0	0
Issues	0	0	0	0
Settlements	0	0	0	0
Balance at end of period	52	46	52	46
Free-standing derivatives, net
Rollforward of Level 3 assets held at fair value on a recurring basis
Balance at beginning of period	(8)	(7)	(7)	(7)
Total gains (losses) included in: Net income	1	1	0	1
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	(1)	0	(1)
Balance at end of period	(7)	(7)	(7)	(7)
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	(313)	(326)	(299)	(323)
Total gains (losses) included in: net income	7	9	(8)	5
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	(1)	(1)
Settlements	2	2	4	4
Balance at end of period	$ (304)	$ (315)	$ (304)	$ (315)