Fair Value (Table of reconciliation for assets and liabilities measured at fair value on a recurring basis using significant unobservable inputs) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,213	$ 1,288	$ 1,281	$ 1,303
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	6	(9)	24	8
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	53	7	65
Purchases	56	273	181	451
Sales	(90)	(278)	(246)	(373)
Settlements	(45)	(56)	(98)	(166)
Transfers into Level 3	17	17	54	55
Transfers out of Level 3	(56)	(57)	(102)	(112)
Balance, Ending, Assets	1,101	1,231	1,101	1,231
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(5)	0	(4)	1
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	186	189	162	204
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(2)	1	(1)	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)	0	(1)	1
Purchases	0	21	12	26
Sales	0	(6)	(12)	(10)
Settlements	(7)	(5)	(21)	(10)
Transfers into Level 3	0	5	37	8
Transfers out of Level 3	(35)	(11)	(35)	(27)
Balance, Ending, Assets	141	194	141	194
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(3)	0	(3)	0
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	86	86	94	71
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1	1	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	1	0	2
Purchases	0	1	0	1
Sales	0	(10)	0	(10)
Settlements	(1)	0	(10)	0
Transfers into Level 3	0	0	0	14
Transfers out of Level 3	0	0	0	0
Balance, Ending, Assets	85	79	85	79
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Residential mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	232	359	189	331
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	(24)	2	(23)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(2)	47	(2)	62
Purchases	0	22	72	47
Sales	0	(174)	0	(174)
Settlements	(11)	(19)	(21)	(40)
Transfers into Level 3	0	0	0	21
Transfers out of Level 3	(13)	(26)	(33)	(39)
Balance, Ending, Assets	207	185	207	185
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	64	126	83	151
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	2	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)	1	0	0
Purchases	9	0	15	0
Sales	0	(60)	0	(60)
Settlements	(1)	(1)	(2)	(2)
Transfers into Level 3	17	12	17	12
Transfers out of Level 3	(2)	(20)	(28)	(44)
Balance, Ending, Assets	87	59	87	59
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Other asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	553	439	655	446
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	2	0	3	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	1	4	10	4
Purchases	47	229	82	377
Sales	(90)	(28)	(234)	(111)
Settlements	(17)	(18)	(20)	(90)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(6)	0	(6)	(1)
Balance, Ending, Assets	490	626	490	626
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(1)	0	(1)
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	849	924	927	928
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	4	(23)	7	(20)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(2)	52	8	66
Purchases	56	251	169	424
Sales	(90)	(262)	(234)	(345)
Settlements	(29)	(38)	(43)	(132)
Transfers into Level 3	17	12	17	33
Transfers out of Level 3	(21)	(46)	(67)	(84)
Balance, Ending, Assets	784	870	784	870
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(1)	0	(1)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,121	1,199	1,183	1,203
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	2	(21)	7	(17)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(3)	53	7	69
Purchases	56	273	181	451
Sales	(90)	(278)	(246)	(365)
Settlements	(37)	(43)	(74)	(142)
Transfers into Level 3	17	17	54	55
Transfers out of Level 3	(56)	(57)	(102)	(111)
Balance, Ending, Assets	1,010	1,143	1,010	1,143
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(3)	(1)	(3)	(1)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	13	2	16	11
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	0	3
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	3	0	0	(4)
Purchases	0	0	0	0
Sales	0	0	0	(8)
Settlements	0	0	0	0
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, Ending, Assets	16	2	16	2
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
Life settlement contracts, included in Other assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	79	87	82	88
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	4	12	17	22
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	0	0	0
Purchases	0	0	0	0
Sales	0	0	0	0
Settlements	(8)	(13)	(24)	(24)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, Ending, Assets	75	86	75	86
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ (2)	1	$ (1)	2
Separate account business [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets				1
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)				0
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)				0
Purchases				0
Sales				0
Settlements				0
Transfers into Level 3				0
Transfers out of Level 3				(1)
Balance, Ending, Assets		$ 0		0
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)				$ 0