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	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	$ 473	$ 1,281
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	4	18
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	3	7
Purchases	62	125
Sales	(16)	(156)
Settlements	(14)	(53)
Transfers into Level 3	2	37
Transfers out of Level 3	(23)	(46)
Balance, Ending, Assets	491	1,213
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	1	1
Corporate and other bonds [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	168	162
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)	4	0
Purchases	53	12
Sales	(16)	(12)
Settlements	(3)	(14)
Transfers into Level 3	0	37
Transfers out of Level 3	(12)	0
Balance, Ending, Assets	193	186
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	2	94
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	0
Purchases	0	0
Sales	0	0
Settlements	0	(9)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	2	86
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	134	189
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	0
Purchases	0	72
Sales	0	0
Settlements	(5)	(10)
Transfers into Level 3	0	0
Transfers out of Level 3	(2)	(20)
Balance, Ending, Assets	128	232
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	22	83
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	1
Purchases	9	6
Sales	0	0
Settlements	0	(1)
Transfers into Level 3	0	0
Transfers out of Level 3	(4)	(26)
Balance, Ending, Assets	27	64
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	53	655
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	1
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	9
Purchases	0	35
Sales	0	(144)
Settlements	0	(3)
Transfers into Level 3	2	0
Transfers out of Level 3	(5)	0
Balance, Ending, Assets	50	553
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Total asset-backed [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	209	927
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	1	3
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	10
Purchases	9	113
Sales	0	(144)
Settlements	(5)	(14)
Transfers into Level 3	2	0
Transfers out of Level 3	(11)	(46)
Balance, Ending, Assets	205	849
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Total Fixed maturity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	379	1,183
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	5
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	4	10
Purchases	62	125
Sales	(16)	(156)
Settlements	(8)	(37)
Transfers into Level 3	2	37
Transfers out of Level 3	(23)	(46)
Balance, Ending, Assets	400	1,121
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	0	0
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Balance, Beginning, Assets	20	16
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	0	0
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	(1)	(3)
Purchases	0	0
Sales	0	0
Settlements	0	0
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	19	13
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	74	82
Net realized investment gains (losses) and net change in unrealized appreciation (depreciation) included in net income (loss)	4	13
Net change in unrealized appreciation (depreciation) included in other comprehensive income (loss)	0	0
Purchases	0	0
Sales	0	0
Settlements	(6)	(16)
Transfers into Level 3	0	0
Transfers out of Level 3	0	0
Balance, Ending, Assets	72	79
Fair Value, Assets Measured on Recurring Basis, Change in Unrealized Gain (Loss)	$ 1	$ 1