Segments of Operations (Details Textuals) (USD $) In Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010
Segments of Operations (Textuals) [Abstract]
Earnings (losses) of managed investment entities attributable to noncontrolling interests	$ (20)	$ (13)	$ (55)	$ (33)
Property and Casualty Insurance [Member]
Segments of Operations (Textuals) [Abstract]
Special charges to increase asbestos and environmental reserves			50
Other Segment [Member]
Segments of Operations (Textuals) [Abstract]
Earnings (losses) of managed investment entities attributable to AFG shareholders, including management fees	6	7	15	15
Earnings (losses) of managed investment entities attributable to noncontrolling interests	(20)	(13)	(55)	(33)
Special charges to increase asbestos and environmental reserves			$ 9