Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
US Treasury and Government [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	$ 15	$ 20
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	0
Financial assets, Ending Balance	15	20
States, municipalities and political subdivisions [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	61	58
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	(4)
Financial assets, Ending Balance	61	54
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	316	371
Total realized/unrealized gains (losses) included in Net income	1	2
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	4	6
Purchases and issuances	0	6
Sales and settlements	(8)	(12)
Transfer into Level 3	32	16
Transfer out of Level 3	(73)	(35)
Financial assets, Ending Balance	272	354
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	28	22
Total realized/unrealized gains (losses) included in Net income	0	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	7
Transfer out of Level 3	0	0
Financial assets, Ending Balance	28	30
Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	75	253
Total realized/unrealized gains (losses) included in Net income	0	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	1	0
Purchases and issuances	50	12
Sales and settlements	(1)	(6)
Transfer into Level 3	81	0
Transfer out of Level 3	0	(15)
Financial assets, Ending Balance	206	245
All other corporate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	335	236
Total realized/unrealized gains (losses) included in Net income	1	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	3	0
Purchases and issuances	1	10
Sales and settlements	(16)	(2)
Transfer into Level 3	0	0
Transfer out of Level 3	(2)	0
Financial assets, Ending Balance	322	244
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	31	37
Total realized/unrealized gains (losses) included in Net income	1	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	2	3
Purchases and issuances	30	9
Sales and settlements	(9)	0
Transfer into Level 3	0	0
Transfer out of Level 3	(14)	0
Financial assets, Ending Balance	41	49
Assets of Managed Investment Entities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	30	40
Total realized/unrealized gains (losses) included in Net income	(1)	(4)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	(6)
Financial assets, Ending Balance	$ 29	$ 30