Shareholders' Equity (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Components of accumulated other comprehensive income
Unrealized holding gains (losses) on securities arising during the period, pretax	$ 122
Unrealized holding gains (losses) on securities arising during the period, tax	(43)
Unrealized holding gains (losses) on securities arising during the period, net of tax	79		158
Unrealized holding gains (losses) on securities arising during the period, attributable to noncontrolling interests	(1)
Unrealized holding gains (losses) on securities arising during the period, attributable to shareholders	78
Reclassification adjustment for realized gains included in net earnings, pretax	(56)	[1]
Reclassification adjustment for realized gains included in net earnings, tax	20	[1]
Reclassification adjustment for realized gains included in net earnings, net of tax	(36)		(28)
Reclassification adjustment for realized gains included in net earnings, attributable to noncontrolling interests		[1]
Reclassification adjustment for realized gains included in net earnings, attributable to shareholders	(36)
Accumulated other comprehensive income, net unrealized gains on securities, beginning balance	823	[2]	578
Other comprehensive income, net unrealized gains on securities, pretax	66		200
Other comprehensive income, net unrealized gains on securities, tax	(23)		(70)
Other comprehensive income, net unrealized gains on securities, net of tax	43		130
Other comprehensive income, net unrealized gains on securities, attributable to noncontrolling interests	(1)		(3)
Other comprehensive income, net unrealized gains on securities, attributable to shareholders	42		127
Accumulated other comprehensive income, net unrealized gains on securities, ending balance	865	[2]	705
Accumulated other comprehensive income, foreign currency translation adjustments, beginning balance	14		10
Other comprehensive income, foreign currency translation adjustments, pretax	(4)		7
Other comprehensive income, foreign currency translation adjustments, net of tax	(4)		7
Other comprehensive income, foreign currency translation adjustments, attributable to noncontrolling interests			(1)
Other comprehensive income, foreign currency translation adjustments, attributable to shareholders	(4)		6
Accumulated other comprehensive income, foreign currency translation adjustments, ending balance	10		16
Accumulated other comprehensive income, pension and other postretirement plans adjustments, beginning balance	(6)		(8)
Other comprehensive income, pension and other postretirement plans adjustments, pretax			1
Other comprehensive income, pension and other postretirement plans adjustments, net of tax			1
Other comprehensive income, pension and other postretirement plans adjustments, attributable to shareholders			1
Accumulated other comprehensive income, pension and other postretirement plans adjustments, ending balance	(6)		(7)
Accumulated other comprehensive income, total, beginning balance	831		580
Other comprehensive income, total, pretax	62		208
Other comprehensive income, total, tax	(23)		(70)
Other comprehensive income, total, net of tax	39		138
Other comprehensive income, total, attributable to noncontrolling interests	(1)		(4)
Other comprehensive income, total, attributable to shareholders	38		134
Accumulated other comprehensive income, total, ending balance	$ 869		$ 714

[1] The reclassification adjustment out of net unrealized gains on securities affected the following lines in AFG’s Consolidated Statement of Earnings: OCI component Affected line in the Consolidated Statement of Earnings Pretax Realized gains on securities Tax Provision for income taxes Attributable to noncontrolling interests Net earnings (loss) attributable to noncontrolling interests

[2] Includes net unrealized gains of $45 million at March 31, 2013 compared to $33 million at December 31, 2012 related to securities for which only the credit portion of an other-than-temporary impairment has been recorded in earnings.