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	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,453	$ 1,873	$ 1,393	$ 1,751
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)		(22)	(5)	17
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(21)	16	(13)	30
Purchases	77	233	685	1,022
Sales	(6)	(126)	(324)	(489)
Settlements	(80)	(80)	(195)	(339)
Transfers into Level 3	17	12	73	54
Transfers out of Level 3	(69)	(423)	(243)	(563)
Balance, Ending, Assets	1,371	1,483	1,371	1,483
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(4)	(38)	(30)	(37)
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	202	488	219	482
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	1	2	7
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)		(4)	(1)	2
Purchases	6	50	129	197
Sales	(6)	(5)	(96)	(118)
Settlements	(8)	(11)	(34)	(43)
Transfers into Level 3	17		43	42
Transfers out of Level 3	(1)	(260)	(51)	(310)
Balance, Ending, Assets	211	259	211	259
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)		(1)	(2)	(1)
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	140	89	96	171
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)			(3)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(3)		1	3
Purchases			122
Sales			(79)
Settlements	(15)		(20)	(85)
Transfers into Level 3			5
Transfers out of Level 3	(27)		(27)
Balance, Ending, Assets	95	89	95	89
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Residential mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	428	443	413	452
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)		(17)	2	(15)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(20)	20	(21)	(2)
Purchases	5	21	116	81
Sales			(10)
Settlements	(21)	(8)	(53)	(24)
Transfers into Level 3			4
Transfers out of Level 3	(22)	(22)	(81)	(55)
Balance, Ending, Assets	370	437	370	437
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)	(18)	(3)	(18)
Commercial mortgage-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	165	166	129	59
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(1)	4		6
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(2)	6	7	14
Purchases	10	12	88	141
Sales				(12)
Settlements	(1)	(17)	(10)	(21)
Transfers into Level 3		11	21	11
Transfers out of Level 3	(14)	(65)	(78)	(81)
Balance, Ending, Assets	157	117	157	117
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Other asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	387	434	368	343
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)		2	3	8
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	1	5	(1)	8
Purchases	56	143	230	501
Sales		(117)	(132)	(293)
Settlements	(6)	(34)	(30)	(93)
Transfers into Level 3
Transfers out of Level 3	(5)	(62)	(5)	(103)
Balance, Ending, Assets	433	371	433	371
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	980	1,043	910	854
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(1)	(11)	5	(1)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(21)	31	(15)	20
Purchases	71	176	434	723
Sales		(117)	(142)	(305)
Settlements	(28)	(59)	(93)	(138)
Transfers into Level 3		11	25	11
Transfers out of Level 3	(41)	(149)	(164)	(239)
Balance, Ending, Assets	960	925	960	925
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(2)	(18)	(5)	(18)
Redeemable preferred stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	25	27	26
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)	1	(1)		(1)
Purchases				53
Sales				(26)
Settlements	(25)		(25)
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets		26		26
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,347	1,647	1,251	1,507
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(1)	(10)	3	6
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(23)	26	(15)	24
Purchases	77	226	685	973
Sales	(6)	(122)	(317)	(449)
Settlements	(76)	(70)	(172)	(266)
Transfers into Level 3	17	11	73	53
Transfers out of Level 3	(69)	(409)	(242)	(549)
Balance, Ending, Assets	1,266	1,299	1,266	1,299
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(2)	(19)	(7)	(19)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	13	93	34	67
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(2)	(19)	(22)	(19)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	2	(10)	2	6
Purchases				26
Sales				(16)
Settlements
Transfers into Level 3
Transfers out of Level 3		(14)	(1)	(14)
Balance, Ending, Assets	13	50	13	50
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(2)	(19)	(22)	(21)
Other invested assets, including derivatives, net
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets		10		10
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales			(1)
Settlements			1
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets		10		10
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Short term investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets		4	6	27
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases		7		23
Sales		(4)	(6)	(4)
Settlements				(39)
Transfers into Level 3		1		1
Transfers out of Level 3
Balance, Ending, Assets		8		8
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Life settlement contracts [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	91	116	100	117
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	3	7	14	30
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales
Settlements	(4)	(10)	(24)	(34)
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	90	113	90	113
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)			(1)	3
Separate account business [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	2	3	2	23
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales				(20)
Settlements
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	2	3	2	3
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)