Income Taxes (Details 3) (USD $) In Millions, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Deferred tax assets:
Federal net operating loss carryforwards	$ 51	$ 51
Foreign underwriting losses	46	42
Insurance claims and reserves	528	431
Employee benefits	91	94
Other, net	36	52
Total deferred tax assets before valuation allowance	752	670
Valuation allowance against deferred tax assets	(101)	(97)
Total deferred tax assets	651	573
Deferred tax liabilities:
Subsidiaries not in AFG's tax return	(58)	(61)
Investment securities	(753)	(441)
Deferred policy acquisition costs	(91)	(204)
Total deferred tax liabilities	(902)	(706)
Net deferred tax liability	$ (251)	$ (133)