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		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,101	$ 1,231	$ 1,281	$ 1,303
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	12	5	36	13
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(13)	(7)	(6)	58
Purchases	82	128	263	579
Sales	(21)	0	(267)	(373)
Settlements	(71)	(67)	(169)	(233)
Transfers into Level 3	0	42	54	97
Transfers out of Level 3	(41)	(77)	(143)	(189)
Balance, Ending, Assets	1,049	1,255	1,049	1,255
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	2	1	0	2
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	141	194	162	204
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	(1)	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	(1)	(1)	0
Purchases	27	4	39	30
Sales	(1)	0	(13)	(10)
Settlements	(11)	(3)	(32)	(13)
Transfers into Level 3	0	0	37	8
Transfers out of Level 3	(3)	(21)	(38)	(48)
Balance, Ending, Assets	153	173	153	173
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	0	0
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	85	79	94	71
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0	1	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	1	0	3
Purchases	0	0	0	1
Sales	0	0	0	(10)
Settlements	0	0	(10)	0
Transfers into Level 3	0	0	0	14
Transfers out of Level 3	(24)	0	(24)	0
Balance, Ending, Assets	61	80	61	80
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	207	185	189	331
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	2	1	4	(22)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(2)	0	(4)	62
Purchases	4	0	76	47
Sales	0	0	0	(174)
Settlements	(7)	(17)	(28)	(57)
Transfers into Level 3	0	11	0	32
Transfers out of Level 3	0	(20)	(33)	(59)
Balance, Ending, Assets	204	160	204	160
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	87	59	83	151
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	5	2	7	4
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(4)	(2)	(4)	(2)
Purchases	8	28	23	28
Sales	0	0	0	(60)
Settlements	(15)	(21)	(17)	(23)
Transfers into Level 3	0	31	17	43
Transfers out of Level 3	(10)	0	(38)	(44)
Balance, Ending, Assets	71	97	71	97
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	490	626	655	446
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1	3	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(6)	(4)	4	0
Purchases	43	80	125	457
Sales	(20)	0	(254)	(111)
Settlements	(32)	(25)	(52)	(115)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	(4)	(36)	(10)	(37)
Balance, Ending, Assets	471	642	471	642
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	(1)	(1)
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	784	870	927	928
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	7	4	14	(16)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(12)	(6)	(4)	60
Purchases	55	108	224	532
Sales	(20)	0	(254)	(345)
Settlements	(54)	(63)	(97)	(195)
Transfers into Level 3	0	42	17	75
Transfers out of Level 3	(14)	(56)	(81)	(140)
Balance, Ending, Assets	746	899	746	899
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	(1)	(1)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,010	1,143	1,183	1,203
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	7	4	14	(13)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(12)	(6)	(5)	63
Purchases	82	112	263	563
Sales	(21)	0	(267)	(365)
Settlements	(65)	(66)	(139)	(208)
Transfers into Level 3	0	42	54	97
Transfers out of Level 3	(41)	(77)	(143)	(188)
Balance, Ending, Assets	960	1,152	960	1,152
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0	(1)	(1)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	16	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)	(1)	(1)	(1)	(5)
Purchases	0	16	0	16
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	15	17	15	17
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	75	86	82	88
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	5	1	22	23
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	(6)	(1)	(30)	(25)
Transfers into Level 3	0	0	0	0
Transfers out of Level 3	0	0	0	0
Balance, Ending, Assets	74	86	74	86
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 2	1	$ 1	3
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