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, 2011	Dec. 31, 2010
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 2,340	$ 2,651
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	21	45
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(16)	133
Purchases	1,436
Sales	(917)
Settlements	(474)
Purchases, sales, issuances and settlements		(204)
Transfers into Level 3	86	78
Transfers out of Level 3	(725)	(363)
Balance, Ending, Assets	1,751	2,340
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(19)	(16)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	2,092	2,467
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(13)	21
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(18)	131
Purchases	1,330
Sales	(865)
Settlements	(400)
Purchases, sales, issuances and settlements		(266)
Transfers into Level 3	81	69
Transfers out of Level 3	(700)	(330)
Balance, Ending, Assets	1,507	2,092
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(23)	(20)
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	624	609
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(11)	9
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)	56
Purchases	484
Sales	(204)
Settlements	(149)
Purchases, sales, issuances and settlements		45
Transfers into Level 3	79	60
Transfers out of Level 3	(340)	(155)
Balance, Ending, Assets	482	624
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(12)	(4)
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	266	756
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)	(1)	15
Purchases	3
Sales
Settlements	(92)
Purchases, sales, issuances and settlements		(507)
Transfers into Level 3		2
Transfers out of Level 3	(5)
Balance, Ending, Assets	171	266
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)
Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,199	1,100
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(5)	6
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(13)	58
Purchases	843
Sales	(658)
Settlements	(159)
Purchases, sales, issuances and settlements		203
Transfers into Level 3	2	7
Transfers out of Level 3	(355)	(175)
Balance, Ending, Assets	854	1,199
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(11)	(16)
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	767	629
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(16)	(10)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(11)	15
Purchases	225
Sales	(290)
Settlements	(60)
Purchases, sales, issuances and settlements		181
Transfers into Level 3
Transfers out of Level 3	(163)	(48)
Balance, Ending, Assets	452	767
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(6)	(13)
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	73	123
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	20	10
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(7)	13
Purchases	81
Sales	(27)
Settlements
Purchases, sales, issuances and settlements		(8)
Transfers into Level 3		7
Transfers out of Level 3	(81)	(72)
Balance, Ending, Assets	59	73
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)		(2)
Other asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	359	348
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(9)	6
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	5	30
Purchases	537
Sales	(341)
Settlements	(99)
Purchases, sales, issuances and settlements		30
Transfers into Level 3	2
Transfers out of Level 3	(111)	(55)
Balance, Ending, Assets	343	359
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(5)	(1)
Redeemable Preferred Stock [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	3	2
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	3	6
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(3)	2
Purchases
Sales	(3)
Settlements
Purchases, sales, issuances and settlements		(7)
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets		3
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	26	11
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(2)	(4)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	2	1
Purchases	66
Sales	(27)
Settlements
Purchases, sales, issuances and settlements		17
Transfers into Level 3	5	8
Transfers out of Level 3	(3)	(7)
Balance, Ending, Assets	67	26
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	(3)	(5)
Derivative and other financial instruments, net [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	25	(11)
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	3	(1)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases	1
Sales	(19)
Settlements
Purchases, sales, issuances and settlements		37
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	10	25
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	2	(1)
Short-term Investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	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	39
Sales
Settlements	(29)
Purchases, sales, issuances and settlements		37
Transfers into Level 3		1
Transfers out of Level 3	(10)	(11)
Balance, Ending, Assets	27	27
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 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	129	130
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	33	29
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales
Settlements	(45)
Purchases, sales, issuances and settlements		(30)
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	117	129
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)	5	10
Discontinued operations investments [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets		16
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)		1
Purchases, sales, issuances and settlements		(2)
Transfers into Level 3
Transfers out of Level 3		(15)
Balance, Ending, Assets
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)
Seperate account business [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	41	38
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	(6)
Settlements
Purchases, sales, issuances and settlements		3
Transfers into Level 3
Transfers out of Level 3	(12)
Balance, Ending, Assets	23	41
Unrealized gains (losses) on Level 3 assets and liabilities held at December 31 recognized in net income (loss)