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	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,281	$ 1,303
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	39	27
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(8)	46
Purchases	303	673
Sales	(276)	(386)
Settlements	(182)	(273)
Transfers into Level 3	79	107
Transfers out of Level 3	(763)	(216)
Balance, Ending, Assets	473	1,281
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(1)	7
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	162	204
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(2)	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(3)	(1)
Purchases	65	33
Sales	(13)	(23)
Settlements	(35)	(16)
Transfers into Level 3	40	18
Transfers out of Level 3	(46)	(55)
Balance, Ending, Assets	168	162
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(2)	0
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	94	71
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	4
Purchases	0	14
Sales	0	(10)
Settlements	(10)	0
Transfers into Level 3	0	14
Transfers out of Level 3	(83)	0
Balance, Ending, Assets	2	94
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Residential mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	189	331
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	5	(21)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(3)	61
Purchases	81	94
Sales	0	(174)
Settlements	(35)	(72)
Transfers into Level 3	14	32
Transfers out of Level 3	(117)	(62)
Balance, Ending, Assets	134	189
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	83	151
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	7	7
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(4)	(6)
Purchases	23	28
Sales	0	(60)
Settlements	(17)	(29)
Transfers into Level 3	17	43
Transfers out of Level 3	(87)	(51)
Balance, Ending, Assets	22	83
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Other asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	655	446
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	3	2
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	3	(6)
Purchases	130	488
Sales	(263)	(111)
Settlements	(52)	(117)
Transfers into Level 3	7	0
Transfers out of Level 3	(430)	(47)
Balance, Ending, Assets	53	655
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(1)
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	927	928
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	15	(12)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(4)	49
Purchases	234	610
Sales	(263)	(345)
Settlements	(104)	(218)
Transfers into Level 3	38	75
Transfers out of Level 3	(634)	(160)
Balance, Ending, Assets	209	927
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	(1)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,183	1,203
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	14	(9)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(7)	52
Purchases	299	657
Sales	(276)	(378)
Settlements	(149)	(234)
Transfers into Level 3	78	107
Transfers out of Level 3	(763)	(215)
Balance, Ending, Assets	379	1,183
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	(2)	(1)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	16	11
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	3
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)	(6)
Purchases	4	16
Sales	0	(8)
Settlements	0	0
Transfers into Level 3	1	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	20	16
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	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	82	88
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	25	33
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	0
Purchases	0	0
Sales	0	0
Settlements	(33)	(39)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	74	82
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1	8
Separate account business [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 0	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
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)		$ 0