Supplementary Insurance Information (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	$ 975	$ 550	$ 901
Reserves for future policy benefits, claims and unpaid losses and LAE	29,362	26,513	23,667
Unearned premiums	1,757	1,651	1,484
Net earned premiums	3,318	3,165	3,189
Net investment income	1,346	1,301	1,225
Benefits, claims, losses and settlement expenses	2,731	2,770	2,614
Amortization of deferred policy acquisition costs	610	700	593
Other operating expenses	1,062	950	878
Net written premiums (excluding life)	3,417	3,227	3,155
Property and Casualty Insurance [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	211	204	189
Reserves for future policy benefits, claims and unpaid losses and LAE	6,410	6,845	6,520
Unearned premiums	1,757	1,651	1,484
Net earned premiums	3,204	2,847	2,759
Net investment income	263	275	291
Benefits, claims, losses and settlement expenses	2,040	1,873	1,744
Amortization of deferred policy acquisition costs	460	423	425
Other operating expenses	607	528	465
Net written premiums (excluding life)	3,341	2,949	2,770
Annuity [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	723	299	560
Reserves for future policy benefits, claims and unpaid losses and LAE	20,944	17,609	15,420
Net investment income	1,034	976	859
Benefits, claims, losses and settlement expenses	531	541	510
Amortization of deferred policy acquisition costs	144	163	114
Other operating expenses	103	68	90
Run-off Long-term Care and Life [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs	41	47	43
Reserves for future policy benefits, claims and unpaid losses and LAE	2,008	2,059	1,478
Net earned premiums	114	119	126
Net investment income	76	69	66
Benefits, claims, losses and settlement expenses	160	225	151
Amortization of deferred policy acquisition costs	6	95	19
Other operating expenses	38	28	20
Net written premiums (excluding life)	76	79	81
Medicare Supplement and Critical Illness [Member]
Supplementary Insurance Information, by Segment [Line Items]
Deferred policy acquisition costs			109
Reserves for future policy benefits, claims and unpaid losses and LAE			249
Net earned premiums		199	304
Net investment income		7	10
Benefits, claims, losses and settlement expenses		131	209
Amortization of deferred policy acquisition costs		19	35
Other operating expenses		34	47
Net written premiums (excluding life)		199	304
Other [Member]
Supplementary Insurance Information, by Segment [Line Items]
Net earned premiums
Net investment income	(27)	(26)	(1)
Other operating expenses	$ 314	$ 292	$ 256