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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 1,288	$ 1,600	$ 1,303	$ 1,393
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(9)	(1)	8	(5)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	53	(1)	65	8
Purchases	273	143	451	608
Sales	(278)	(153)	(373)	(318)
Settlements	(56)	(50)	(166)	(115)
Transfers into Level 3	17	30	55	56
Transfers out of Level 3	(57)	(115)	(112)	(174)
Balance, Ending, Assets	1,231	1,453	1,231	1,453
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)		(10)	1	(26)
Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	1,199		1,203
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(21)		(17)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	53		69
Purchases	273		451
Sales	(278)		(365)
Settlements	(43)		(142)
Transfers into Level 3	17		55
Transfers out of Level 3	(57)		(111)
Balance, Ending, Assets	1,143		1,143
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)		(1)
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	189		204
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)			1
Purchases	21		26
Sales	(6)		(10)
Settlements	(5)		(10)
Transfers into Level 3	5		8
Transfers out of Level 3	(11)		(27)
Balance, Ending, Assets	194		194
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	86		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)	1		2
Purchases	1		1
Sales	(10)		(10)
Settlements
Transfers into Level 3			14
Transfers out of Level 3
Balance, Ending, Assets	79		79
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	359		331
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(24)		(23)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	47		62
Purchases	22		47
Sales	(174)		(174)
Settlements	(19)		(40)
Transfers into Level 3			21
Transfers out of Level 3	(26)		(39)
Balance, Ending, Assets	185		185
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	126		151
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)	1
Purchases
Sales	(60)		(60)
Settlements	(1)		(2)
Transfers into Level 3	12		12
Transfers out of Level 3	(20)		(44)
Balance, Ending, Assets	59		59
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	439		446
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)			1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	4		4
Purchases	229		377
Sales	(28)		(111)
Settlements	(18)		(90)
Transfers into Level 3
Transfers out of Level 3			(1)
Balance, Ending, Assets	626		626
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)		(1)
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	924		928
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	(23)		(20)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	52		66
Purchases	251		424
Sales	(262)		(345)
Settlements	(38)		(132)
Transfers into Level 3	12		33
Transfers out of Level 3	(46)		(84)
Balance, Ending, Assets	870		870
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	(1)		(1)
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	2		11
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)			(4)
Purchases
Sales			(8)
Settlements
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	2		2
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)
Life settlement contracts, included in Other assets [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	87		88
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	12		22
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales
Settlements	(13)		(24)
Transfers into Level 3
Transfers out of Level 3
Balance, Ending, Assets	86		86
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)	1		2
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)
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)
Purchases
Sales
Settlements
Transfers into Level 3
Transfers out of Level 3			(1)
Balance, Ending, Assets
Unrealized gains (losses) on Level 3 assets and liabilities held at balance sheet date recognized in net income (loss)