Fair Value Measurements (Details Textual) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013 professional	Dec. 31, 2012	Dec. 31, 2011
Fair Value Measurements (Textual) [Abstract]
AFG's internal investment professionals	20
Level 3 assets as a percentage of total assets measured at fair value	3.00%
Percentage of level 3 assets that were priced using non-binding broker quotes	78.00%
Level 3 assets that were priced using non-binding broker quotes	$ 699
Percentage of internally developed Level 3 assets to total assets (are less than)	0.50%
Percentage of internally developed Level 3 assets to Shareholders' equity (are less than)	2.00%
Total realized/unrealized losses included in net income on liabilities still outstanding	7	(125)	(3)
Fixed-indexed annuities (embedded derivative) [Member]
Fair Value Measurements (Textual) [Abstract]
Fair value of derivatives in annuity benefits accumulated measured using a discounted cash flow approach	$ 804
Fixed-indexed annuities (embedded derivative) [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	4.00%
Fixed-indexed annuities (embedded derivative) [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	16.00%
Fixed-indexed annuities (embedded derivative), majority of future years [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	6.00%
Fixed-indexed annuities (embedded derivative), majority of future years [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	12.00%