Fair Value Measurements (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 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	$ 15	$ 20
Total realized/unrealized gains (losses) included in Net income	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	15	20	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	54	61	58
Total realized/unrealized gains (losses) included in Net income	0	0	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(1)	0	(1)
Purchases and issuances	0	10	0	10
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	(4)
Financial assets, Ending Balance	61	63	61	63
Residential Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	272	354	316	371
Total realized/unrealized gains (losses) included in Net income	2	2	3	4
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	2	(7)	6	(1)
Purchases and issuances	0	0	0	6
Sales and settlements	(7)	(17)	(15)	(29)
Transfer into Level 3	6	9	38	25
Transfer out of Level 3	(19)	(12)	(92)	(47)
Financial assets, Ending Balance	256	329	256	329
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	28	30	28	22
Total realized/unrealized gains (losses) included in Net income	0	(2)	0	(1)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	0	0	0
Sales and settlements	0	0	0	0
Transfer into Level 3	0	0	0	7
Transfer out of Level 3	0	0	0	0
Financial assets, Ending Balance	28	28	28	28
Asset-backed Securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	206	245	75	253
Total realized/unrealized gains (losses) included in Net income	3	2	3	3
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(2)	1	(2)
Purchases and issuances	10	0	60	12
Sales and settlements	(15)	(39)	(16)	(45)
Transfer into Level 3	0	0	81	0
Transfer out of Level 3	0	(26)	0	(41)
Financial assets, Ending Balance	204	180	204	180
All other corporate [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	322	244	335	236
Total realized/unrealized gains (losses) included in Net income	4	0	5	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	(10)	3	(10)
Purchases and issuances	20	44	21	55
Sales and settlements	(30)	(4)	(46)	(6)
Transfer into Level 3	0	25	0	24
Transfer out of Level 3	(3)	(4)	(5)	(4)
Financial assets, Ending Balance	313	295	313	295
Equity securities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	41	49	31	37
Total realized/unrealized gains (losses) included in Net income	0	0	1	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	2	(1)	4	2
Purchases and issuances	16	39	46	48
Sales and settlements	0	0	(9)	0
Transfer into Level 3	22	0	22	0
Transfer out of Level 3	0	(9)	(14)	(9)
Financial assets, Ending Balance	81	78	81	78
Assets of Managed Investment Entities [Member]
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Financial assets, Beginning Balance	29	30	30	40
Total realized/unrealized gains (losses) included in Net income	(1)	1	(2)	(3)
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0	0	0
Purchases and issuances	0	6	0	6
Sales and settlements	(1)	(6)	(1)	(6)
Transfer into Level 3	0	0	0	0
Transfer out of Level 3	0	0	0	(6)
Financial assets, Ending Balance	$ 27	$ 31	$ 27	$ 31