Shareholders' Equity (Details 1) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015		Mar. 31, 2014
Components of accumulated other comprehensive income
Unrealized holding gains (losses) on securities arising during the period, pretax	$ 106		$ 211
Unrealized holding gains (losses) on securities arising during the period, tax	(37)		(74)
Unrealized holding gains (losses) on securities arising during the period, net of tax	69		137
Unrealized holding gains (losses) on securities arising during the period, attributable to noncontrolling interests	(1)		(3)
Unrealized holding gains (losses) on securities arising during the period, attributable to shareholders	68		134
Reclassification adjustment for realized (gains) losses included in net earnings, pretax	(19)	[1]	(18)	[1]
Reclassification adjustment for realized (gains) losses included in net earnings, tax	7	[1]	6	[1]
Reclassification adjustment for realized (gains) losses included in net earnings, net of tax	(12)		(12)
Reclassification adjustment for realized (gains) losses included in net earnings, attributable to noncontrolling interests	0	[1]
Reclassification adjustment for realized (gains) losses included in net earnings, attributable to shareholders	(12)		(12)
Accumulated Other Comprehensive Income (Loss), Net of Tax [Roll Forward]
Accumulated other comprehensive income, net unrealized gains on securities, beginning balance	743	[2]	563
Other comprehensive income, net unrealized gains on securities, pretax	87		193
Other comprehensive income, net unrealized gains on securities, tax	(30)		(68)
Total net unrealized gains on securities	57		125
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	56		122
Accumulated other comprehensive income, net unrealized gains on securities, ending balance	799	[2]	685
Accumulated other comprehensive income, net unrealized gains (losses) on cash flow hedges, beginning balance	0
Other comprehensive income, net unrealized gains (losses) on cash flow hedges, pretax	1
Other comprehensive income, net unrealized gains (losses) on cash flow hedges, tax	0
Other comprehensive income, net unrealized gains (losses) on cash flow hedges, net of tax	1		0
Other comprehensive income, net unrealized gains (losses) on cash flow hedges, attributable to noncontrolling interests	0
Other comprehensive income, net unrealized gains (losses) on cash flow hedges, attributable to shareholders	1
Accumulated other comprehensive income, net unrealized gains (losses) on cash flow hedges, ending balance	1
Accumulated other comprehensive income, foreign currency translation adjustments, beginning balance	(8)		1
Other comprehensive income, foreign currency translation adjustments, pretax	(8)		(5)
Other comprehensive income, foreign currency translation adjustments, net of tax	(8)		(5)
Other comprehensive income, foreign currency translation adjustments, attributable to noncontrolling interests	0		0
Other comprehensive income, foreign currency translation adjustments, attributable to shareholders	(8)		(5)
Accumulated other comprehensive income, foreign currency translation adjustments, ending balance	(16)		(4)
Accumulated other comprehensive income, pension and other postretirement plans adjustments, beginning balance	(8)		(4)
Other comprehensive income, pension and other postretirement plans adjustments, pretax	0		0
Other comprehensive income, pension and other postretirement plans adjustments, tax	0		0
Other comprehensive income, pension and other postretirement plans adjustments, net of tax	0		0
Other comprehensive income, pension and other postretirement plans adjustments, attributable to shareholders	0		0
Accumulated other comprehensive income, pension and other postretirement plans adjustments, ending balance	(8)		(4)
Accumulated other comprehensive income, total, beginning balance	727		560
Other comprehensive income, total, pretax	80		188
Other comprehensive income, total, tax	(30)		(68)
Other comprehensive income, net of tax	50		120
Other comprehensive income, total, attributable to noncontrolling interests	(1)		(3)
Other comprehensive income, total, attributable to shareholders	49		117
Accumulated other comprehensive income, total, ending balance	$ 776		$ 677

[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 $57 million at March 31, 2015 compared to $58 million at December 31, 2014 related to securities for which only the credit portion of an other-than-temporary impairment has been recorded in earnings.