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, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,303	$ 1,393
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	27	(5)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	46
Purchases	673	804
Sales	(386)	(414)
Settlements	(273)	(275)
Transfers into Level 3	107	94
Transfers out of Level 3	(216)	(294)
Balance, Ending, Assets	1,281	1,303
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	7	(36)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,203	1,251
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(9)	9
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	52	(3)
Purchases	657	801
Sales	(378)	(405)
Settlements	(234)	(251)
Transfers into Level 3	107	94
Transfers out of Level 3	(215)	(293)
Balance, Ending, Assets	1,183	1,203
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)	(7)
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	204	219
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	2	3
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)
Purchases	33	142
Sales	(23)	(116)
Settlements	(16)	(44)
Transfers into Level 3	18	51
Transfers out of Level 3	(55)	(51)
Balance, Ending, Assets	162	204
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)		(2)
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	71	96
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	(2)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	4	4
Purchases	14	122
Sales	(10)	(79)
Settlements		(61)
Transfers into Level 3	14	18
Transfers out of Level 3		(27)
Balance, Ending, Assets	94	71
Residential mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	331	413
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(21)	4
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	61	(14)
Purchases	94	116
Sales	(174)	(10)
Settlements	(72)	(75)
Transfers into Level 3	32	4
Transfers out of Level 3	(62)	(107)
Balance, Ending, Assets	189	331
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)		(3)
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	151	129
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	7
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(6)	11
Purchases	28	107
Sales	(60)	(3)
Settlements	(29)	(11)
Transfers into Level 3	43	21
Transfers out of Level 3	(51)	(103)
Balance, Ending, Assets	83	151
Other asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	446	368
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	2	5
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(6)	(4)
Purchases	488	314
Sales	(111)	(197)
Settlements	(117)	(35)
Transfers out of Level 3	(47)	(5)
Balance, Ending, Assets	655	446
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)	(2)
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	928	910
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(12)	9
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	49	(7)
Purchases	610	537
Sales	(345)	(210)
Settlements	(218)	(121)
Transfers into Level 3	75	25
Transfers out of Level 3	(160)	(215)
Balance, Ending, Assets	927	928
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)	(5)
Redeemable Preferred Stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets		26
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)		(1)
Settlements		(25)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	11	34
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	3	(27)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(6)	3
Purchases	16	2
Sales	(8)
Transfers out of Level 3		(1)
Balance, Ending, Assets	16	11
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)		(27)
Other invested assets, including derivatives, net
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Sales		(1)
Settlements		1
Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets		6
Sales		(6)
Life settlement contracts, included in Other assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	88	100
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	33	13
Settlements	(39)	(25)
Balance, Ending, Assets	82	88
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	8	(2)
Separate account business [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1	2
Purchases		1
Sales		(2)
Transfers out of Level 3	(1)
Balance, Ending, Assets		$ 1