Goodwill and Other Intangibles (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		12 Months Ended					12 Months Ended
	Sep. 30, 2012	Sep. 30, 2010	Dec. 31, 2012	Dec. 31, 2010	Dec. 31, 2010 Property and Casualty [Member]	Dec. 31, 2012 Property and Casualty [Member]	Dec. 31, 2011 Property and Casualty [Member]	Dec. 31, 2012 Annuity [Member]	Dec. 31, 2010 Annuity [Member]	Dec. 31, 2010 Medicare Supplement and Critical Illness [Member]	Dec. 31, 2012 Medicare Supplement and Critical Illness [Member]
Changes in the carrying value of goodwill by reporting segment
Goodwill, Beginning balance			$ 186	$ 208	$ 152	$ 152	$ 152	$ 34	$ 34	$ 22	$ 0
Goodwill, Impairment charge		(22)		(22)	0				0	(22)
Goodwill, Sale of subsidiary	(1)		(1)					(1)
Goodwill, Ending balance			$ 185	$ 186	$ 152	$ 152	$ 152	$ 33	$ 34	$ 0	$ 0