Fair Value Measurements (Details 3) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
US Treasury and Government [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	$ 15	$ 20	$ 0
Total realized/unrealized gains (losses) included in Net income	0	(2)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(3)	0
Purchases and issuances	0	0	20
Sales and settlements	0	0	0
Transfer into Level 3	0	0	0
Transfer out of Level 3	0	0	0
Financial assets, Ending Balance	15	15	20
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	61	58	83
Total realized/unrealized gains (losses) included in Net income	(1)	(1)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(2)	4
Purchases and issuances	30	10	19
Sales and settlements	0	0	(7)
Transfer into Level 3	10	0	8
Transfer out of Level 3	0	(4)	(49)
Financial assets, Ending Balance	100	61	58
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	316	371	361
Total realized/unrealized gains (losses) included in Net income	4	5	5
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	3	24	17
Purchases and issuances	13	6	96
Sales and settlements	(31)	(53)	(45)
Transfer into Level 3	111	86	228
Transfer out of Level 3	(116)	(123)	(291)
Financial assets, Ending Balance	300	316	371
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	28	22	19
Total realized/unrealized gains (losses) included in Net income	(1)	(1)	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(1)	2
Purchases and issuances	0	0	0
Sales and settlements	0	0	0
Transfer into Level 3	17	8	0
Transfer out of Level 3	0	0	0
Financial assets, Ending Balance	44	28	22
Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	75	253	228
Total realized/unrealized gains (losses) included in Net income	3	4	7
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	(2)	(3)	8
Purchases and issuances	99	12	55
Sales and settlements	(39)	(57)	(36)
Transfer into Level 3	117	11	14
Transfer out of Level 3	(27)	(145)	(23)
Financial assets, Ending Balance	226	75	253
All other corporate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	335	236	291
Total realized/unrealized gains (losses) included in Net income	2	1	3
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	13	(14)	9
Purchases and issuances	102	113	86
Sales and settlements	(73)	(17)	(35)
Transfer into Level 3	172	24	15
Transfer out of Level 3	(5)	(8)	(133)
Financial assets, Ending Balance	546	335	236
Trading fixed maturities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance			1
Total realized/unrealized gains (losses) included in Net income			0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)			0
Purchases and issuances			0
Sales and settlements			0
Transfer into Level 3			0
Transfer out of Level 3			(1)
Financial assets, Ending Balance			0
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	31	37	11
Total realized/unrealized gains (losses) included in Net income	1	(1)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	2	6	2
Purchases and issuances	62	53	30
Sales and settlements	(9)	(12)	0
Transfer into Level 3	22	0	13
Transfer out of Level 3	(16)	(52)	(19)
Financial assets, Ending Balance	93	31	37
Assets of Managed Investment Entities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Financial assets, Beginning Balance	30	40	44
Total realized/unrealized gains (losses) included in Net income	(3)	(5)	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0
Purchases and issuances	6	8	20
Sales and settlements	(2)	(7)	(14)
Transfer into Level 3	0	0	13
Transfer out of Level 3	0	(6)	(23)
Financial assets, Ending Balance	$ 31	$ 30	$ 40