Acquisitions and Sales of Businesses (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended			0 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Apr. 01, 2014		Dec. 31, 2011
Business Acquisition [Line Items]
Total purchase price	$ 267	$ 0	$ 0
Allocation of excess purchase price:
Goodwill	201	185	185			186
Summit Holding Southeast, Inc [Member]
Business Acquisition [Line Items]
Total purchase price				259
Tangible assets acquired:
Cash and cash equivalents				1,078
Fixed maturities, available for sale				92
Recoverables from reinsurers				116
Agents’ balances and premiums receivable				41
Deferred tax assets, net				67	[1]
Other receivables				21
Other assets				11
Total tangible assets acquired				1,426
Liabilities acquired:
Unpaid losses and loss adjustment expenses				1,142
Unearned premiums				3
Payable to reinsurers				3
Other liabilities				66
Total liabilities acquired				1,214
Net tangible assets acquired, at fair value				212
Excess purchase price over net tangible assets acquired				47
Allocation of excess purchase price:
Intangible assets acquired				47	[2]
Deferred tax on intangible assets acquired				(16)	[1]
Goodwill				$ 16

[1] Included with AFG’s net deferred tax liabilities, which are included in Other liabilities in AFG’s Consolidated Balance Sheet.

[2] Included in Other assets in AFG’s Consolidated Balance Sheet.