American Financial (AFG) 10-Q 7 May 15 2015 Q1 Quarterly report Financial data

Document_and_Entity_Informatio

Document and Entity Information	3 Months Ended
	Mar. 31, 2015	1-May-15
Document and Entity Information [Abstract]
Entity Registrant Name	AMERICAN FINANCIAL GROUP INC
Entity Central Index Key	1042046
Document Type	10-Q
Document Period End Date	31-Mar-15
Amendment Flag	FALSE
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q1
Current Fiscal Year End Date	-19
Entity Filer Category	Large Accelerated Filer
Entity Common Stock, Shares Outstanding		87,908,873

Consolidated_Balance_Sheet_Una

Consolidated Balance Sheet (Unaudited) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Assets:
Cash and cash equivalents	$1,212	$1,343
Investments:
Fixed maturities, available for sale at fair value (amortized cost — $30,090 and $29,074)	31,968	30,734
Fixed maturities, trading at fair value	273	266
Equity securities, available for sale at fair value (cost — $1,306 and $1,283)	1,530	1,501
Equity securities, trading at fair value	180	195
Mortgage loans	1,091	1,117
Policy loans	226	228
Real estate and other investments	904	826
Total cash and investments	37,384	36,210
Recoverables from reinsurers	3,046	3,238
Prepaid reinsurance premiums	475	469
Agents’ balances and premiums receivable	864	889
Deferred policy acquisition costs	756	821
Assets of managed investment entities	3,279	3,108
Other receivables	641	910
Variable annuity assets (separate accounts)	667	662
Other assets	994	1,027
Goodwill	201	201
Total assets	48,307	47,535
Liabilities and Equity:
Unpaid losses and loss adjustment expenses	7,636	7,872
Unearned premiums	1,936	1,956
Annuity benefits accumulated	24,411	23,764
Life, accident and health reserves	2,195	2,175
Payable to reinsurers	494	645
Liabilities of managed investment entities	2,952	2,819
Long-term debt	1,061	1,061
Variable annuity liabilities (separate accounts)	667	662
Other liabilities	1,855	1,527
Total liabilities	43,207	42,481
Shareholders’ equity:
Common Stock, no par value — 200,000,000 shares authorized — 87,885,715 and 87,708,793 shares outstanding	88	88
Capital surplus	1,173	1,152
Retained earnings:
Appropriated — managed investment entities	0	-2
Unappropriated	2,886	2,914
Accumulated other comprehensive income, net of tax	776	727
Total shareholders’ equity	4,923	4,879
Noncontrolling interests	177	175
Total equity	5,100	5,054
Total liabilities and equity	$48,307	$47,535

Consolidated_Balance_Sheet_Una1

Consolidated Balance Sheet (Unaudited) (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, except Share data, unless otherwise specified
Statement of Financial Position [Abstract]
Fixed maturities, available for sale at amortized cost	$30,090	$29,074
Equity securities, available for sale at cost	$1,306	$1,283
Common Stock, par value (USD per share)	$0	$0
Common Stock, shares authorized	200,000,000	200,000,000
Common Stock, shares outstanding	87,885,715	87,708,793

Consolidated_Statement_of_Earn

Consolidated Statement of Earnings (Unaudited) (USD $)	3 Months Ended
In Millions, except Per Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Revenues:
Property and casualty insurance net earned premiums	$946	$754
Life, accident and health net earned premiums	25	28
Net investment income	388	361
Realized gains (losses) on:
Securities	19	19
Subsidiaries	-162	0
Income (loss) of managed investment entities:
Investment income	34	28
Gain (loss) on change in fair value of assets/liabilities	-3	0
Other income	47	21
Total revenues	1,294	1,211
Costs and Expenses:
Losses and loss adjustment expenses	576	429
Commissions and other underwriting expenses	313	267
Annuity benefits	184	168
Life, accident and health benefits	32	43
Annuity and supplemental insurance acquisition expenses	38	35
Interest charges on borrowed money	20	18
Expenses of managed investment entities	24	20
Other expenses	77	70
Total costs and expenses	1,264	1,050
Earnings before income taxes	30	161
Provision for income taxes	5	54
Net earnings, including noncontrolling interests	25	107
Less: Net earnings attributable to noncontrolling interests	6	4
Net Earnings Attributable to Shareholders	19	103
Earnings Attributable to Shareholders per Common Share:
Basic (USD per share)	$0.22	$1.15
Diluted (USD per share)	$0.21	$1.13
Average number of Common Shares:
Basic (shares)	87.6	89.6
Diluted (shares)	89.4	91.6
Cash dividends per Common Share (USD per share)	$0.25	$0.22
Supplemental disclosure of Realized gains on securities:
Realized gains before impairments	23	20
Losses on securities with impairment	-4	-1
Non-credit portion recognized in other comprehensive income (loss)	0	0
Impairment charges recognized in earnings	-4	-1
Total realized gains on securities	$19	$19

Consolidated_Statement_of_Comp

Consolidated Statement of Comprehensive Income (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Statement of Comprehensive Income [Abstract]
Net earnings, including noncontrolling interests	$25	$107
Net unrealized gains on securities:
Unrealized holding gains on securities arising during the period	69	137
Reclassification adjustment for realized gains included in net earnings	-12	-12
Total net unrealized gains on securities	57	125
Net unrealized gains on cash flow hedges	1	0
Foreign currency translation adjustments	-8	-5
Other comprehensive income, net of tax	50	120
Total comprehensive income, net of tax	75	227
Less: Comprehensive income attributable to noncontrolling interests	7	7
Comprehensive income attributable to shareholders	$68	$220

Consolidated_Statement_of_Chan

Consolidated Statement of Changes in Equity (Unaudited) (USD $)	Total	Total	Common Shares	Common Stock and Capital Surplus	Retained Earnings Approp.	Retained Earnings Unapprop.	Accumulated Other Comprehensive Inc. (Loss)	Noncontrolling Interests
In Millions, except Share data, unless otherwise specified	USD ($)	USD ($)		USD ($)	USD ($)	USD ($)	USD ($)	USD ($)
Beginning Balance at Dec. 31, 2013	$4,769	$4,599		$1,213	$49	$2,777	$560	$170
Beginning Balance, shares at Dec. 31, 2013			89,513,386
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net earnings	107	103				103		4
Other comprehensive income	120	117					117	3
Allocation of losses of managed investment entities	0	0			0			0
Dividends on Common Stock	-19	-19				-19
Shares issued:
Exercise of stock options, shares			323,473
Exercise of stock options	11	11		11
Other benefit plans, shares			192,525
Other benefit plans	5	5		5
Dividend reinvestment plan, shares			3,343
Stock-based compensation expense	5	5		5
Shares acquired and retired, shares			-419,938
Shares acquired and retired	-24	-24		-6		-18
Shares exchanged - benefit plans, shares			-23,790
Shares exchanged - benefit plans	-1	-1				-1
Ending Balance at Mar. 31, 2014	4,973	4,796		1,228	49	2,842	677	177
Ending Balance, shares at Mar. 31, 2014			89,588,999
Beginning Balance at Dec. 31, 2014	5,054	4,879		1,240	-2	2,914	727	175
Beginning Balance, shares at Dec. 31, 2014	87,708,793		87,708,793
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change for variable interest entities	2	2			2
Net earnings	25	19				19		6
Other comprehensive income	50	49					49	1
Dividends on Common Stock	-22	-22				-22
Shares issued:
Exercise of stock options, shares			489,001
Exercise of stock options	20	20		20
Other benefit plans, shares			233,224
Other benefit plans	4	4		4
Dividend reinvestment plan, shares			3,606
Dividend reinvestment plan	0	0		0
Stock-based compensation expense	5	5		5
Shares acquired and retired, shares			-516,276
Shares acquired and retired	-31	-31		-8		-23
Shares exchanged - benefit plans, shares			-32,633
Shares exchanged - benefit plans	-2	-2				-2
Other	-5							-5
Ending Balance at Mar. 31, 2015	$5,100	$4,923		$1,261	$0	$2,886	$776	$177
Ending Balance, shares at Mar. 31, 2015	87,885,715		87,885,715

Consolidated_Statement_of_Cash

Consolidated Statement of Cash Flows (Unaudited) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Operating Activities:
Net earnings, including noncontrolling interests	$25	$107
Adjustments:
Depreciation and amortization	31	27
Annuity benefits	184	168
Realized (gains) losses on investing activities	133	-19
Net (purchases) sales of trading securities	-4	6
Deferred annuity and life policy acquisition costs	-44	-50
Change in:
Reinsurance and other receivables	483	459
Other assets	27	-5
Insurance claims and reserves	-242	-226
Payable to reinsurers	-151	-108
Other liabilities	-41	-60
Managed investment entities’ assets/liabilities	-25	-99
Other operating activities, net	21	4
Net cash provided by operating activities	397	204
Investing Activities:
Purchases of fixed maturities	-1,605	-1,355
Purchases of equity securities	-79	-137
Purchases of mortgage loans	-31	-113
Purchases of real estate, property and equipment	-19	-14
Purchases of business	0	-8
Proceeds from maturities and redemptions of fixed maturities	736	782
Proceeds from repayments of mortgage loans	59	6
Proceeds from sales of fixed maturities	32	151
Proceeds from sales of equity securities	79	51
Proceeds from sales of real estate, property and equipment	23	1
Managed investment entities:
Purchases of investments	-258	-244
Proceeds from sales and redemptions of investments	149	442
Other investing activities, net	-54	12
Net cash used in investing activities	-968	-426
Financing Activities:
Annuity receipts	813	967
Annuity surrenders, benefits and withdrawals	-443	-395
Net transfers from variable annuity assets	10	6
Issuances of managed investment entities’ liabilities	103	45
Retirement of managed investment entities’ liabilities	-4	-133
Issuances of Common Stock	19	11
Repurchases of Common Stock	-31	-24
Cash dividends paid on Common Stock	-22	-19
Other financing activities, net	-5	1
Net cash provided by financing activities	440	459
Net Change in Cash and Cash Equivalents	-131	237
Cash and cash equivalents at beginning of period	1,343	1,639
Cash and cash equivalents at end of period	$1,212	$1,876

Accounting_Policies

Accounting Policies	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Accounting Policies	Accounting Policies
	Basis of Presentation   The accompanying consolidated financial statements for American Financial Group, Inc. (“AFG”) and its subsidiaries are unaudited; however, management believes that all adjustments (consisting only of normal recurring accruals unless otherwise disclosed herein) necessary for fair presentation have been made. The results of operations for interim periods are not necessarily indicative of results to be expected for the year. The financial statements have been prepared in accordance with the instructions to Form 10-Q and, therefore, do not include all information and footnotes necessary to be in conformity with U.S. generally accepted accounting principles (“GAAP”).
	Certain reclassifications have been made to prior periods to conform to the current year’s presentation. All significant intercompany balances and transactions have been eliminated. The results of operations of companies since their formation or acquisition are included in the consolidated financial statements. Events or transactions occurring subsequent to March 31, 2015, and prior to the filing of this Form 10-Q, have been evaluated for potential recognition or disclosure herein.
	The preparation of the financial statements requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Changes in circumstances could cause actual results to differ materially from those estimates.
	Fair Value Measurements   Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants on the measurement date. The standards establish a hierarchy of valuation techniques based on whether the assumptions that market participants would use in pricing the asset or liability (“inputs”) are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect AFG’s assumptions about the assumptions market participants would use in pricing the asset or liability. Other than recording an estimated loss on the pending sale of its long-term care business (see Note B — “Acquisitions and Sale of Businesses”), AFG did not have any significant nonrecurring fair value measurements in the first three months of 2015.
	Investments   Fixed maturity and equity securities classified as “available for sale” are reported at fair value with unrealized gains and losses included in accumulated other comprehensive income (“AOCI”) in AFG’s Balance Sheet. Fixed maturity and equity securities classified as “trading” are reported at fair value with changes in unrealized holding gains or losses during the period included in net investment income. Mortgage and policy loans are carried primarily at the aggregate unpaid balance.
	Premiums and discounts on fixed maturity securities are amortized using the interest method; mortgage-backed securities (“MBS”) are amortized over a period based on estimated future principal payments, including prepayments. Prepayment assumptions are reviewed periodically and adjusted to reflect actual prepayments and changes in expectations.
	Gains or losses on securities are determined on the specific identification basis. When a decline in the value of a specific investment is considered to be other-than-temporary at the balance sheet date, a provision for impairment is charged to earnings (included in realized gains (losses) on securities) and the cost basis of that investment is reduced. If management can assert that it does not intend to sell an impaired fixed maturity security and it is not more likely than not that it will have to sell the security before recovery of its amortized cost basis, then the other-than-temporary impairment is separated into two components: (i) the amount related to credit losses (recorded in earnings) and (ii) the amount related to all other factors (recorded in other comprehensive income). The credit-related portion of an other-than-temporary impairment is measured by comparing a security’s amortized cost to the present value of its current expected cash flows discounted at its effective yield prior to the impairment charge. Both components are shown in the Statement of Earnings. If management intends to sell an impaired security, or it is more likely than not that it will be required to sell the security before recovery, an impairment charge to earnings is recorded to reduce the amortized cost of that security to fair value.
	Derivatives   Derivatives included in AFG’s Balance Sheet are recorded at fair value. Changes in fair value of derivatives are included in earnings, unless the derivatives are designated as cash flow hedges. Derivatives that do not qualify for hedge accounting under GAAP consist primarily of (i) components of certain fixed maturity securities (primarily interest-only MBS) and (ii) the equity-based component of certain annuity products (included in annuity benefits accumulated) and related call options (included in other investments) designed to be consistent with the characteristics of the liabilities and used to mitigate the risk embedded in those annuity products.
	To qualify for hedge accounting, at the inception of a derivative contract, AFG formally documents the relationship between the terms of the hedge and the hedged items and its risk management objective. This documentation includes defining how hedge effectiveness and ineffectiveness will be measured on a retrospective and prospective basis. Changes in the fair value of derivatives that are designated and qualify as highly effective cash flow hedges are recorded in AOCI and are reclassified into earnings when the variability of the cash flows from the hedged items impact earnings. Any hedge ineffectiveness is immediately recorded in current period earnings. When the change in the fair value of a qualifying cash flow hedge is included in earnings, it is included in the same line item in the Consolidated Statement of Earnings as the cash flows from the hedged item. Qualifying highly effective cash flow hedges include interest rate swaps, which are used to mitigate interest rate risk related to certain floating-rate securities included in AFG’s portfolio of fixed maturity securities.
	Goodwill   Goodwill represents the excess of cost of subsidiaries over AFG’s equity in their underlying net assets. Goodwill is not amortized, but is subject to an impairment test at least annually. An entity is not required to complete the quantitative annual goodwill impairment test on a reporting unit if the entity elects to perform a qualitative analysis and determines that it is more likely than not that the reporting unit’s fair value exceeds its carrying amount.
	Reinsurance   Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured policies. AFG’s property and casualty insurance subsidiaries report as assets (i) the estimated reinsurance recoverable on paid and unpaid losses, including an estimate for losses incurred but not reported, and (ii) amounts paid or due to reinsurers applicable to the unexpired terms of policies in force. Payable to reinsurers includes ceded premiums due to reinsurers as well as ceded premiums retained by AFG’s property and casualty insurance subsidiaries under contracts to fund ceded losses as they become due. AFG’s insurance subsidiaries also assume reinsurance from other companies. Earnings on reinsurance assumed is recognized based on information received from ceding companies.
	A subsidiary cedes life insurance policies to a third party on a funds withheld basis whereby the subsidiary retains the assets (securities) associated with the reinsurance contract. Interest is credited to the reinsurer based on the actual investment performance of the retained assets. This reinsurance contract is considered to contain an embedded derivative (that must be adjusted to fair value) because the yield on the payable is based on a specific block of the ceding company’s assets, rather than the overall creditworthiness of the ceding company. AFG determined that changes in the fair value of the underlying portfolio of fixed maturity securities is an appropriate measure of the value of the embedded derivative. The securities related to this contract are classified as “trading.” The adjustment to fair value on the embedded derivative offsets the investment income recorded on the adjustment to fair value of the related trading portfolio.
	Deferred Policy Acquisition Costs (“DPAC”)   Policy acquisition costs (principally commissions, premium taxes and certain underwriting and policy issuance costs) directly related to the successful acquisition or renewal of an insurance contract are deferred. DPAC also includes capitalized costs associated with sales inducements offered to fixed annuity policyholders such as enhanced interest rates and premium and persistency bonuses.
	For the property and casualty companies, DPAC is limited based upon recoverability without any consideration for anticipated investment income and is charged against income ratably over the terms of the related policies. A premium deficiency is recognized if the sum of expected claims costs, claims adjustment expenses and unamortized acquisition costs exceed the related unearned premiums. A premium deficiency is first recognized by charging any unamortized acquisition costs to expense to the extent required to eliminate the deficiency. If the premium deficiency is greater than unamortized acquisition costs, a liability is accrued for the excess deficiency and reported with unpaid losses and loss adjustment expenses.
	DPAC related to annuities is deferred to the extent deemed recoverable and amortized, with interest, in relation to the present value of actual and expected gross profits on the policies. Expected gross profits consist principally of estimated future investment margin (estimated future net investment income less interest credited on policyholder funds) and surrender, mortality, and other life and annuity policy charges, less death, annuitization and guaranteed withdrawal benefits in excess of account balances and estimated future policy administration expenses. To the extent that realized gains and losses result in adjustments to the amortization of DPAC related to annuities, such adjustments are reflected as components of realized gains (losses) on securities.
	DPAC related to traditional life and health insurance is amortized over the expected premium paying period of the related policies, in proportion to the ratio of annual premium revenues to total anticipated premium revenues. See “Life, Accident and Health Reserves” below for details on the impact of loss recognition on the accounting for traditional life and health insurance contracts.
	DPAC includes the present value of future profits on business in force of annuity and life, accident and health insurance companies acquired (“PVFP”). PVFP represents the portion of the costs to acquire companies that is allocated to the value of the right to receive future cash flows from insurance contracts existing at the date of acquisition. PVFP is amortized with interest in relation to expected gross profits of the acquired policies for annuities and universal life products and in relation to the premium paying period for traditional life and health insurance products.
	DPAC and certain other balance sheet amounts related to annuity, long-term care and life businesses are also adjusted, net of tax, for the change in expense that would have been recorded if the unrealized gains (losses) from securities had actually been realized. These adjustments are included in unrealized gains (losses) on marketable securities, a component of AOCI in AFG’s Balance Sheet.
	Managed Investment Entities   A company is considered the primary beneficiary of, and therefore must consolidate, a variable interest entity (“VIE”) based primarily on its ability to direct the activities of the VIE that most significantly impact that entity’s economic performance and the obligation to absorb losses of, or receive benefits from, the entity that could potentially be significant to the VIE.
	AFG manages, and has investments in, collateralized loan obligations (“CLOs”) that are VIEs (see Note H — “Managed Investment Entities”). Both the management fees (payment of which is subordinate to other obligations of the CLOs) and the investments in the CLOs are considered variable interests. AFG has determined that it is the primary beneficiary of the CLOs because (i) its role as asset manager gives it the power to direct the activities that most significantly impact the economic performance of the CLOs and (ii) it has exposure to CLO losses (through its investments in the CLO debt tranches) and the right to receive benefits (through its subordinated management fees and returns on its investments), both of which could potentially be significant to the CLOs.
	In February 2015, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2015-02, which amends certain consolidation accounting guidance, including the VIE guidance that applies to collateralized financing entities such as CLOs. The new guidance, which AFG intends to adopt effective January 1, 2016, will affect how fee arrangements with CLO asset managers impact the determination of the primary beneficiary of these entities. Due to the significance of AFG’s investments in the CLOs that it manages, management does not expect the new guidance to impact the consolidation of its currently outstanding CLOs. In addition, the new guidance impacts the consolidation analysis that applies to limited partnerships and similar entities. Management is currently evaluating its investments in limited partnerships and similar entities under the new guidance.
	Because AFG has no right to use the CLO assets and no obligation to pay the CLO liabilities, the assets and liabilities of the CLOs are shown separately in AFG’s Balance Sheet. AFG has elected the fair value option for reporting on the CLO assets and liabilities to improve the transparency of financial reporting related to the CLOs. The net gain or loss from accounting for the CLO assets and liabilities at fair value is presented separately in AFG’s Statement of Earnings.
	Effective January 1, 2015, AFG adopted (on a modified retrospective basis) ASU 2014-13, which addresses the diversity in practice regarding the accounting for assets and liabilities of a consolidated collateralized financing entity (such as a CLO) when an election has been made to account for that entity’s assets and liabilities at fair value. The fair values of a CLO’s assets may differ from the separately measured fair values of its liabilities even though the CLO liabilities only have recourse to the CLO assets. Under the new guidance, AFG has elected to set the carrying value of the CLO liabilities equal to the fair value of the CLO assets (which have more observable fair values) as an alternative to reporting those liabilities at a separately measured fair value. CLO earnings attributable to AFG’s shareholders continue to be measured by the change in the fair value of AFG’s investments in the CLOs and management fees earned.
	Prior to the adoption of this guidance, measuring both the CLO assets and CLO liabilities at separately determined fair values resulted in a difference between the carrying value of the CLO assets and the carrying value of the CLO liabilities that was not attributable to AFG’s ownership interest in the CLOs and CLO earnings (losses) that were not attributable to AFG’s shareholders. Accordingly, in periods prior to 2015, the difference between the fair value of the CLO assets and the fair value of the CLO liabilities was recorded as “appropriated retained earnings — managed investment entities” in AFG’s Balance Sheet and the earnings (losses) that were not attributable to AFG’s shareholders were included in net earnings (loss) attributable to noncontrolling interests in AFG’s Statement of Earnings.
	Under the guidance adopted in 2015, there is no longer any excess carrying value of CLO assets over the carrying value of CLO liabilities to be reported as “appropriated retained earnings — managed investment entities” in AFG’s Balance Sheet or any CLO earnings to be attributed to noncontrolling interests in AFG’s Statement of Earnings. In accordance with the guidance, the amount reported as “appropriated retained earnings — managed investment entities” at December 31, 2014 was reclassified to “liabilities of managed investment entities” on January 1, 2015 as the cumulative effect of an accounting change. While the new guidance impacted the presentation of individual CLO-related line items in AFG’s Statement of Earnings, it had no overall impact on AFG’s Net Earnings Attributable to Shareholders.
	At March 31, 2015, assets and liabilities of managed investment entities included $222 million in assets and $177 million in liabilities of a temporary warehousing entity that was established in connection with the formation of a new CLO that is expected to close in the second quarter of 2015. Upon closing, all warehoused assets are expected to be transferred to the new CLO and the liabilities will be repaid.
	Unpaid Losses and Loss Adjustment Expenses   The net liabilities stated for unpaid claims and for expenses of investigation and adjustment of unpaid claims represent management’s best estimate and are based upon (i) the accumulation of case estimates for losses reported prior to the close of the accounting period on direct business written; (ii) estimates received from ceding reinsurers and insurance pools and associations; (iii) estimates of unreported losses (including possible development on known claims) based on past experience; (iv) estimates based on experience of expenses for investigating and adjusting claims; and (v) the current state of the law and coverage litigation. Establishing reserves for asbestos, environmental and other mass tort claims involves considerably more judgment than other types of claims due to, among other things, inconsistent court decisions, an increase in bankruptcy filings as a result of asbestos-related liabilities, novel theories of coverage, and judicial interpretations that often expand theories of recovery and broaden the scope of coverage.
	Loss reserve liabilities are subject to the impact of changes in claim amounts and frequency and other factors. Changes in estimates of the liabilities for losses and loss adjustment expenses are reflected in the Statement of Earnings in the period in which determined. Despite the variability inherent in such estimates, management believes that the liabilities for unpaid losses and loss adjustment expenses are adequate.
	Annuity Benefits Accumulated   Annuity receipts and benefit payments are recorded as increases or decreases in annuity benefits accumulated rather than as revenue and expense. Increases in this liability for interest credited are charged to expense and decreases for policy charges are credited to other income.
	For certain products, annuity benefits accumulated also includes reserves for accrued persistency and premium bonuses, guaranteed withdrawals and excess benefits expected to be paid on future deaths and annuitizations (“EDAR”). The liabilities for EDAR and guaranteed withdrawals are accrued for and modified using assumptions consistent with those used in determining DPAC and DPAC amortization, except that amounts are determined in relation to the present value of total expected assessments. Total expected assessments consist principally of estimated future investment margin, surrender, mortality, and other life and annuity policy charges, and unearned revenues once they are recognized as income.
	Annuity benefits accumulated also includes amounts advanced from the Federal Home Loan Bank of Cincinnati.
	Unearned Revenue   Certain upfront policy charges on annuities are deferred as unearned revenue (included in other liabilities) and recognized in net earnings using the same assumptions and estimated gross profits used to amortize DPAC.
	Life, Accident and Health Reserves   Liabilities for future policy benefits under traditional life, accident and health policies are computed using the net level premium method. Computations are based on the original projections of investment yields, mortality, morbidity and surrenders and include provisions for unfavorable deviations unless a loss recognition event (premium deficiency) occurs. Claim reserves and liabilities established for accident and health claims are modified as necessary to reflect actual experience and developing trends.
	For long-duration contracts (such as traditional life and long-term care policies), loss recognition occurs when, based on current expectations as of the measurement date, existing contract liabilities plus the present value of future premiums (including reasonably expected rate increases) are not expected to cover the present value of future claims payments and related settlement and maintenance costs (excluding overhead) as well as unamortized acquisition costs. If a block of business is determined to be in loss recognition, a charge is recorded in earnings in an amount equal to the excess of the present value of expected future claims costs and unamortized acquisition costs over existing reserves plus the present value of expected future premiums (with no provision for adverse deviation). The charge is recorded first to reduce unamortized acquisition costs and then as an additional reserve (if unamortized acquisition costs have been reduced to zero).
	In addition, reserves for traditional life and long-term care policies are subject to adjustment for loss recognition charges that would have been recorded if the unrealized gains from securities had actually been realized. This adjustment is included in unrealized gains (losses) on marketable securities, a component of AOCI in AFG’s Balance Sheet.
	Variable Annuity Assets and Liabilities   Separate accounts related to variable annuities represent the fair value of deposits invested in underlying investment funds on which AFG earns a fee. Investment funds are selected and may be changed only by the policyholder, who retains all investment risk.
	AFG’s variable annuity contracts contain a guaranteed minimum death benefit (“GMDB”) to be paid if the policyholder dies before the annuity payout period commences. In periods of declining equity markets, the GMDB may exceed the value of the policyholder’s account. A GMDB liability is established for future excess death benefits using assumptions together with a range of reasonably possible scenarios for investment fund performance that are consistent with DPAC capitalization and amortization assumptions.
	Premium Recognition   Property and casualty premiums are earned generally over the terms of the policies on a pro rata basis. Unearned premiums represent that portion of premiums written which is applicable to the unexpired terms of policies in force. On reinsurance assumed from other insurance companies or written through various underwriting organizations, unearned premiums are based on information received from such companies and organizations. For traditional life, accident and health products, premiums are recognized as revenue when legally collectible from policyholders. For interest-sensitive life and universal life products, premiums are recorded in a policyholder account, which is reflected as a liability. Revenue is recognized as amounts are assessed against the policyholder account for mortality coverage and contract expenses.
	Noncontrolling Interests   For Balance Sheet purposes, noncontrolling interests represents the interests of shareholders other than AFG in consolidated entities. In the Statement of Earnings, net earnings and losses attributable to noncontrolling interests represents such shareholders’ interest in the earnings and losses of those entities.
	Income Taxes   Deferred income taxes are calculated using the liability method. Under this method, deferred income tax assets and liabilities are determined based on differences between financial reporting and tax bases and are measured using enacted tax rates. A valuation allowance is established to reduce total deferred tax assets to an amount that will more likely than not be realized.
	AFG recognizes the tax benefits of uncertain tax positions only when the position is more likely than not to be sustained under examination by the appropriate taxing authority. Interest and penalties on AFG’s reserve for uncertain tax positions are recognized as a component of tax expense.
	Stock-Based Compensation   All share-based grants are recognized as compensation expense on a straight-line basis over their vesting periods based on their calculated fair value at the date of grant. AFG uses the Black-Scholes pricing model to measure the fair value of employee stock options. See Note K — “Shareholders’ Equity” for further information.
	Benefit Plans   AFG provides retirement benefits to qualified employees of participating companies through the AFG 401(k) Retirement and Savings Plan, a defined contribution plan. AFG makes all contributions to the retirement fund portion of the plan and matches a percentage of employee contributions to the savings fund. Company contributions are expensed in the year for which they are declared. AFG and many of its subsidiaries provide health care and life insurance benefits to eligible retirees. AFG also provides postemployment benefits to former or inactive employees (primarily those on disability) who were not deemed retired under other company plans. The projected future cost of providing these benefits is expensed over the period employees earn such benefits.
	Earnings Per Share   Although basic earnings per share only considers shares of common stock outstanding during the period, the calculation of diluted earnings per share includes the following adjustments to weighted average common shares related to stock-based compensation plans: first three months of 2015 and 2014 — 1.8 million and 2.0 million, respectively.
	AFG’s weighted average diluted shares outstanding excludes the following anti-dilutive potential common shares related to stock compensation plans: first three months of 2015 and 2014 — 1.3 million and 0.6 million, respectively. Adjustments to net earnings attributable to shareholders in the calculation of diluted earnings per share were nominal in the 2015 and 2014 periods.
	Statement of Cash Flows   For cash flow purposes, “investing activities” are defined as making and collecting loans and acquiring and disposing of debt or equity instruments and property and equipment. “Financing activities” include obtaining resources from owners and providing them with a return on their investments, borrowing money and repaying amounts borrowed. Annuity receipts, surrenders, benefits and withdrawals are also reflected as financing activities. All other activities are considered “operating.” Short-term investments having original maturities of three months or less when purchased are considered to be cash equivalents for purposes of the financial statements.

Acquisitions_and_Sale_of_Busin

Acquisitions and Sale of Businesses	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Acquisitions and Sale of Businesses	Acquisitions and Sale of Businesses
	Acquisition of Summit Holding Southeast, Inc. On April 1, 2014, AFG acquired Summit Holding Southeast, Inc. and its related companies (“Summit”), from Liberty Mutual Insurance for $259 million using cash on hand at the parent company. Immediately following the acquisition, AFG made a capital contribution of $140 million, bringing its total capital investment in the Summit business to $399 million. Summit is based in Lakeland, Florida and is a leading provider of specialty workers’ compensation solutions in the southeastern United States, which generated $539 million in net written premiums in 2014, including $410 million after the acquisition date. Summit continues to operate under the Summit brand as a member of AFG’s Great American Insurance Group. Summit is included in the Specialty casualty sub-segment and generated $129 million in net earned premiums and $5 million in underwriting profit in the first three months of 2015.
	Acquisition of Renewal Rights On March 27, 2014, AFG completed a renewal rights agreement with Selective Insurance Company of America to acquire Selective’s pooled public entity book of business for $8 million. At the acquisition date, this book of business had approximately $38 million in in-force gross written premiums. The acquired business generated $33 million of gross written premiums and $23 million of net written premiums in 2014.
	Sale of Long-term Care Business AFG ceased new sales of long-term care insurance, which is included in the run-off long-term care and life segment, in January 2010. AFG has continued to service and accept renewal premiums on its outstanding policies, which are guaranteed renewable. On April 13, 2015, AFG reached an agreement to sell all of its run-off long-term care insurance business to HC2 Holdings, Inc. (“HC2”) for an initial payment of $7 million in cash and HC2 securities (subject to adjustment based on certain items, including operating results through the closing date). AFG may also receive up to $13 million of additional proceeds from HC2 in the future based on the release of certain statutory liabilities of the legal entities sold by AFG. The legal entities involved in the transaction, United Teacher Associates Insurance Company and Continental General Insurance Company, contain all of AFG’s long-term care insurance reserves, as well as smaller blocks of annuity and life insurance business. The transaction is expected to close in the third quarter of 2015, subject to customary conditions, including receipt of required regulatory approvals.
	Including the significant tax benefit from the sale, AFG expects to receive after-tax proceeds of between $105 million and $115 million from the transaction (based on final proceeds received and final net assets at closing), excluding any potential additional proceeds from the release of statutory liabilities.
	Based on the status of ongoing negotiations at the end of the quarter, management determined that the potential sale of the run-off long-term care business met the GAAP “held for sale” criteria as of March 31, 2015. Accordingly, AFG recorded a loss in the first quarter of 2015 to establish a liability (included in other liabilities in AFG’s Balance Sheet) equal to the excess of the net carrying value of the assets and liabilities to be disposed over the estimated net sale proceeds. The loss may be adjusted at the closing date based on the final proceeds received and final net assets disposed. At March 31, 2015, the carrying value of the assets and liabilities to be disposed represented approximately 4% of both AFG’s assets and liabilities and are detailed in the table below.
	Under accounting guidance effective on January 1, 2015, only disposals of components of an entity that represent a strategic shift and that have a major effect on a reporting entity’s operations and financial results are reported as discontinued operations. Due to the run-off nature of the business and the immaterial expected impact on AFG’s results of operations, the pending sale of AFG’s long-term care insurance business is not reported as a discontinued operation.
	The estimated impact of the third quarter sale of the run-off long-term care insurance business on AFG’s financial statements is shown below (in millions):
		March 31, 2015
	Estimated sale proceeds (*)	$	14
	Assets of businesses sold:
	Cash and investments	$	1,397
	Recoverables from reinsurers	603
	Deferred policy acquisition costs	15
	Other receivables	14
	Other assets	7
	Goodwill	2
	Total assets	2,038
	Liabilities of businesses sold:
	Annuity benefits accumulated	270
	Life, accident and health reserves	1,537
	Other liabilities	27
	Total liabilities	1,834
	Reclassify net unrealized gain on marketable securities	28
	Net assets of businesses sold	$	176
	Pretax loss on subsidiaries	$	(162	)
	(*)	Includes fair value of the potential additional consideration and is shown net of estimated expenses.
	Revenues, costs and expenses, and earnings before income taxes for the subsidiaries to be sold were (in millions):
		Three months ended March 31,
		2015			2014
	Life, accident and health net earned premiums:
	Long-term care	$	17		$	19
	Life operations	3			3
	Net investment income	18			21
	Realized gains (losses) on securities and other income	(2		)	1
	Total revenues	36			44
	Annuity benefits	2			2
	Life, accident and health benefits:
	Long-term care	21			29
	Life operations	3			3
	Annuity and supplemental insurance acquisition expenses	3			3
	Other expenses	4			4
	Total costs and expenses	33			41
	Earnings before income taxes	$	3		$	3

Segments_of_Operations

Segments of Operations	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segments of Operations	Segments of Operations
	AFG manages its business as four segments: (i) Property and casualty insurance, (ii) Annuity, (iii) Run-off long-term care and life and (iv) Other, which includes holding company costs and the operations attributable to the noncontrolling interests of the managed investment entities.
	AFG reports its property and casualty insurance business in the following Specialty sub-segments: (i) Property and transportation, which includes physical damage and liability coverage for buses, trucks and recreational vehicles, inland and ocean marine, agricultural-related products and other property coverages, (ii) Specialty casualty, which includes primarily excess and surplus, general liability, executive liability, professional liability, umbrella and excess liability, specialty coverage
	in targeted markets, customized programs for small to mid-sized businesses and workers’ compensation insurance, and (iii) Specialty financial, which includes risk management insurance programs for leasing and financing institutions (including collateral and lender-placed mortgage property insurance), surety and fidelity products and trade credit insurance. Premiums and underwriting profit included under Other specialty represent business assumed by AFG’s internal reinsurance program from the operations that make up AFG’s other Specialty sub-segments and amortization of deferred gains on retroactive reinsurance transactions related to the sales of businesses in prior years. AFG’s annuity business markets traditional fixed and fixed-indexed annuities in the retail, financial institutions and education markets. AFG’s reportable segments and their components were determined based primarily upon similar economic characteristics, products and services. The following tables (in millions) show AFG’s revenues and earnings before income taxes by segment and sub-segment.
		Three months ended March 31,
		2015			2014
	Revenues
	Property and casualty insurance:
	Premiums earned:
	Specialty
	Property and transportation	$	313		$	301
	Specialty casualty	490			313
	Specialty financial	120			117
	Other specialty	23			23
	Total premiums earned	946			754
	Net investment income	79			67
	Other income	6			2
	Total property and casualty insurance	1,031			823
	Annuity:
	Net investment income	292			275
	Other income	24			18
	Total annuity	316			293
	Run-off long-term care and life	46			51
	Other	44			25
	Total revenues before realized gains (loss)	1,437			1,192
	Realized gains on securities	19			19
	Realized loss on subsidiaries	(162		)	—
	Total revenues	$	1,294		$	1,211
		Three months ended March 31,
		2015			2014
	Earnings Before Income Taxes
	Property and casualty insurance:
	Underwriting:
	Specialty
	Property and transportation	$	7		$	6
	Specialty casualty	28			38
	Specialty financial	22			10
	Other specialty	3			5
	Other lines	—			(1		)
	Total underwriting	60			58
	Investment and other income, net	73			54
	Total property and casualty insurance	133			112
	Annuity	75			73
	Run-off long-term care and life	4			(2		)
	Other (*)	(39		)	(41		)
	Total earnings before realized gains (loss) and income taxes	173			142
	Realized gains on securities	19			19
	Realized loss on subsidiaries	(162		)	—
	Total earnings before income taxes	$	30		$	161
	(*)	Includes holding company expenses. Also includes earnings of managed investment entities attributable to noncontrolling interest of less than $1 million for the first three months of 2014. Following the adoption of new guidance in the first quarter of 2015, there are no longer earnings of managed investment entities that are attributable to noncontrolling interests. See Note A — “Accounting Policies — Managed Investment Entities.”

Fair_Value_Measurements

Fair Value Measurements	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Fair Value Measurements	Fair Value Measurements
	Accounting standards for measuring fair value are based on inputs used in estimating fair value. The three levels of the hierarchy are as follows:
	Level 1 — Quoted prices for identical assets or liabilities in active markets (markets in which transactions occur with sufficient frequency and volume to provide pricing information on an ongoing basis). AFG’s Level 1 financial instruments consist primarily of publicly traded equity securities and highly liquid government bonds for which quoted market prices in active markets are available and short-term investments of managed investment entities.
	Level 2 — Quoted prices for similar instruments in active markets; quoted prices for identical or similar assets or liabilities in inactive markets (markets in which there are few transactions, the prices are not current, price quotations vary substantially over time or among market makers, or in which little information is released publicly); and valuations based on other significant inputs that are observable in active markets. AFG’s Level 2 financial instruments include separate account assets, corporate and municipal fixed maturity securities, mortgage-backed securities (“MBS”) and investments of managed investment entities priced using observable inputs. Level 2 inputs include benchmark yields, reported trades, corroborated broker/dealer quotes, issuer spreads and benchmark securities. When non-binding broker quotes can be corroborated by comparison to similar securities priced using observable inputs, they are classified as Level 2.
	Level 3 — Valuations derived from market valuation techniques generally consistent with those used to estimate the fair values of Level 2 financial instruments in which one or more significant inputs are unobservable or when the market for a security exhibits significantly less liquidity relative to markets supporting Level 2 fair value measurements. The unobservable inputs may include management’s own assumptions about the assumptions market participants would use based on the best information available in the circumstances. AFG’s Level 3 is comprised of financial instruments whose fair value is estimated based on non-binding broker quotes or internally developed using significant inputs not based on, or corroborated by, observable market information, and prior to 2015 certain liabilities of the CLOs.
	Under new guidance adopted in the first quarter of 2015, discussed in Note A — “Accounting Policies — Managed Investment Entities,” AFG has elected to set the carrying value of the CLO liabilities equal to the fair value of the CLO assets (which have more observable fair values) as an alternative to reporting those liabilities at separately measured fair values. Following the adoption of the new guidance, the CLO liabilities are categorized within the fair value hierarchy on the same basis (proportionally) as the related CLO assets. Since the portion of the CLO liabilities allocated to Level 3 is derived from the fair value of the CLO assets, beginning with the first quarter of 2015, these amounts are excluded from the progression of Level 3 financial instruments.
	AFG’s management is responsible for the valuation process and uses data from outside sources (including nationally recognized pricing services and broker/dealers) in establishing fair value. AFG’s internal investment professionals are a group of approximately 20 analysts whose primary responsibility is to manage AFG’s investment portfolio. These professionals monitor individual investments as well as overall industries and are active in the financial markets on a daily basis. The group is led by AFG’s chief investment officer, who reports directly to one of AFG’s Co-CEOs. Valuation techniques utilized by pricing services and prices obtained from external sources are reviewed by AFG’s internal investment professionals who are familiar with the securities being priced and the markets in which they trade to ensure the fair value determination is representative of an exit price. To validate the appropriateness of the prices obtained, these investment managers consider widely published indices (as benchmarks), recent trades, changes in interest rates, general economic conditions and the credit quality of the specific issuers. In addition, the Company communicates directly with the pricing service regarding the methods and assumptions used in pricing, including verifying, on a test basis, the inputs used by the service to value specific securities.
	In April 2015, AFG reached an agreement to sell all of its run-off long-term care insurance business. As discussed in Note B — “Acquisitions and Sale of Businesses,” AFG recorded a loss in the first quarter of 2015 to write down the net carrying value of the assets and liabilities to be disposed to the estimated net sale proceeds of $14 million (estimated fair value less costs to sell). The estimate of fair value was derived using significant unobservable inputs (Level 3).
	Assets and liabilities measured and carried at fair value in the financial statements are summarized below (in millions):
		Level 1			Level 2			Level 3			Total
	31-Mar-15
	Assets:
	Available for sale (“AFS”) fixed maturities:
	U.S. Government and government agencies	$	123		$	192		$	15		$	330
	States, municipalities and political subdivisions	—			7,045			61			7,106
	Foreign government	—			184			—			184
	Residential MBS	—			4,019			306			4,325
	Commercial MBS	—			2,359			44			2,403
	Asset-backed securities (“ABS”)	—			4,013			211			4,224
	Corporate and other	38			12,775			583			13,396
	Total AFS fixed maturities	161			30,587			1,220			31,968
	Trading fixed maturities	13			260			—			273
	Equity securities	1,388			238			84			1,710
	Assets of managed investment entities (“MIE”)	120			3,130			29			3,279
	Variable annuity assets (separate accounts) (*)	—			667			—			667
	Other investments — derivatives	—			318			—			318
	Total assets accounted for at fair value	$	1,682		$	35,200		$	1,333		$	38,215
	Liabilities:
	Liabilities of managed investment entities	$	108		$	2,818		$	26		$	2,952
	Derivatives in annuity benefits accumulated	—			—			1,243			1,243
	Other liabilities — derivatives	—			13			—			13
	Total liabilities accounted for at fair value	$	108		$	2,831		$	1,269		$	4,208
	31-Dec-14
	Assets:
	Available for sale fixed maturities:
	U.S. Government and government agencies	$	164		$	174		$	15		$	353
	States, municipalities and political subdivisions	—			6,647			100			6,747
	Foreign government	—			194			—			194
	Residential MBS	—			4,142			300			4,442
	Commercial MBS	—			2,407			44			2,451
	Asset-backed securities	—			3,661			226			3,887
	Corporate and other	36			12,078			546			12,660
	Total AFS fixed maturities	200			29,303			1,231			30,734
	Trading fixed maturities	12			254			—			266
	Equity securities	1,306			297			93			1,696
	Assets of managed investment entities	174			2,903			31			3,108
	Variable annuity assets (separate accounts) (*)	—			662			—			662
	Other investments — derivatives	—			322			—			322
	Total assets accounted for at fair value	$	1,692		$	33,741		$	1,355		$	36,788
	Liabilities:
	Liabilities of managed investment entities	$	118		$	—		$	2,701		$	2,819
	Derivatives in annuity benefits accumulated	—			—			1,160			1,160
	Other liabilities — derivatives	—			13			—			13
	Total liabilities accounted for at fair value	$	118		$	13		$	3,861		$	3,992
	(*)    Variable annuity liabilities equal the fair value of variable annuity assets.
	Transfers between Level 1 and Level 2 for all periods presented were a result of increases or decreases in trade frequency. During the first three months of 2015, there was one common stock and two perpetual preferred stocks with aggregate fair values of $53 million and $5 million, respectively, transferred from Level 2 to Level 1. During the first three months of 2014, eight perpetual preferred stocks with an aggregate fair value of $55 million were transferred from Level 1 to Level 2.
	Approximately 3.5% of the total assets carried at fair value on March 31, 2015, were Level 3 assets. Approximately 75% ($990 million) of the Level 3 assets were priced using non-binding broker quotes, for which there is a lack of transparency as to the inputs used to determine fair value. Details as to the quantitative inputs are neither provided by the brokers nor otherwise reasonably obtainable by AFG. Since internally developed Level 3 asset fair values represent less than 1% of the total assets measured at fair value and approximately 6% of AFG’s shareholders’ equity, changes in unobservable inputs used to determine internally developed fair values would not have a material impact on AFG’s financial position.
	The only significant Level 3 assets or liabilities carried at fair value in the financial statements that were not measured using broker quotes are the derivatives embedded in AFG’s fixed-indexed annuity liabilities, which are measured using a discounted cash flow approach and had a fair value of $1.24 billion at March 31, 2015. The following table presents information about the unobservable inputs used by management in determining fair value of these embedded derivatives. See Note F — “Derivatives.”
	Unobservable Input		Range
	Adjustment for insurance subsidiary’s credit risk		0.40% – 1.75% over the risk free rate
	Risk margin for uncertainty in cash flows		0.52% reduction in the discount rate
	Surrenders		4% – 16% of indexed account value
	Partial surrenders		2% – 10% of indexed account value
	Annuitizations		1% – 1.5% of indexed account value
Deaths		1.5% – 3.0% of indexed account value
Budgeted option costs		2.0% – 3.25% of indexed account value
The range of adjustments for insurance subsidiary’s credit risk reflects credit spread variations across the yield curve. The range of projected surrender rates reflects the specific surrender charges and other features of AFG’s individual fixed-indexed annuity products with an expected range of 5% to 11% in the majority of future calendar years (4% to 16% over all periods). Increasing the budgeted option cost or risk margin for uncertainty in cash flows assumptions in the table above would increase the fair value of the fixed-indexed annuity embedded derivatives, while increasing any of the other unobservable inputs in the table above would decrease the fair value of the embedded derivatives.
Changes in balances of Level 3 financial assets and liabilities carried at fair value during the first three months of 2015 and 2014 are presented below (in millions). The transfers into and out of Level 3 were due to changes in the availability of market observable inputs. All transfers are reflected in the table at fair value as of the end of the reporting period.
							Total realized/unrealized
							gains (losses) included in
	Balance at December 31, 2014			Impact of			Net			Other			Purchases			Sales and			Transfer			Transfer			Balance at March 31, 2015
				accounting			income			comprehensive			and			settlements			into			out of
				change (*)						income (loss)			issuances						Level 3			Level 3
AFS fixed maturities:
U.S. government agency	$	15		$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	15
State and municipal	100			—			—			—			—			—			—			(39		)	61
Residential MBS	300			—			(1		)	3			—			(7		)	41			(30		)	306
Commercial MBS	44			—			—			—			—			—			—			—			44
Asset-backed securities	226			—			—			—			5			(41		)	21			—			211
Corporate and other	546			—			—			6			44			(13		)	—			—			583
Equity securities	93			—			—			(2		)	10			—			—			(17		)	84
Assets of MIE	31			—			(2		)	—			—			—			—			—			29
Liabilities of MIE	(2,701		)	2,701			—			—			—			—			—			—			—
Embedded derivatives	(1,160		)	—			(50		)	—			(47		)	14			—			—			(1,243		)
(*)	The impact of implementing new guidance adopted in 2015, as discussed above and in Note A — “Accounting Policies — Managed Investment Entities.”
				Total realized/unrealized
				gains (losses) included in
	Balance at December 31, 2013			Net			Other			Purchases			Sales and			Transfer			Transfer			Balance at March 31, 2014
				income			comprehensive			and			settlements			into			out of
							income (loss)			issuances						Level 3			Level 3
AFS fixed maturities:
U.S. government agency	$	15		$	—		$	—		$	—		$	—		$	—		$	—		$	15
State and municipal	61			—			—			—			—			—			—			61
Residential MBS	316			1			4			—			(8		)	32			(73		)	272
Commercial MBS	28			—			—			—			—			—			—			28
Asset-backed securities	75			—			1			50			(1		)	81			—			206
Corporate and other	335			1			3			1			(16		)	—			(2		)	322
Equity securities	31			1			2			30			(9		)	—			(14		)	41
Assets of MIE	30			(1		)	—			—			—			—			—			29
Liabilities of MIE (*)	(2,411		)	1			—			(45		)	133			—			—			(2,322		)
Embedded derivatives	(804		)	(54		)	—			(55		)	9			—			—			(904		)
(*)	Total realized/unrealized gains (losses) included in net income includes gains of $4 million related to liabilities outstanding as of March 31, 2014. See Note H — “Managed Investment Entities.”
Fair Value of Financial Instruments   The carrying value and fair value of financial instruments that are not carried at fair value in the financial statements are summarized below (in millions):
	Carrying			Fair			Level 1			Level 2			Level 3
	Value			Value
31-Mar-15
Financial assets:
Cash and cash equivalents	$	1,212		$	1,212		$	1,212		$	—		$	—
Mortgage loans	1,091			1,100			—			—			1,100
Policy loans	226			226			—			—			226
Total financial assets not accounted for at fair value	$	2,529		$	2,538		$	1,212		$	—		$	1,326
Financial liabilities:
Annuity benefits accumulated (*)	$	24,209		$	23,966		$	—		$	—		$	23,966
Long-term debt	1,061			1,197			—			1,123			74
Total financial liabilities not accounted for at fair value	$	25,270		$	25,163		$	—		$	1,123		$	24,040
31-Dec-14
Financial assets:
Cash and cash equivalents	$	1,343		$	1,343		$	1,343		$	—		$	—
Mortgage loans	1,117			1,124			—			—			1,124
Policy loans	228			228			—			—			228
Total financial assets not accounted for at fair value	$	2,688		$	2,695		$	1,343		$	—		$	1,352
Financial liabilities:
Annuity benefits accumulated (*)	$	23,561		$	23,187		$	—		$	—		$	23,187
Long-term debt	1,061			1,180			—			1,106			74
Total financial liabilities not accounted for at fair value	$	24,622		$	24,367		$	—		$	1,106		$	23,261
(*)	Excludes life contingent annuities in the payout phase.
The carrying amount of cash and cash equivalents approximates fair value. Fair values for mortgage loans are estimated by discounting the future contractual cash flows using the current rates at which similar loans would be made to borrowers with similar credit ratings. The fair value of policy loans is estimated to approximate carrying value; policy loans have no defined maturity dates and are inseparable from insurance contracts. The fair value of annuity benefits was estimated based on expected cash flows discounted using forward interest rates adjusted for the Company’s credit risk and includes the impact of maintenance expenses and capital costs. Fair values of long-term debt are based primarily on quoted market prices.

Investments

Investments	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Investments	Investments
	Available for sale fixed maturities and equity securities at March 31, 2015 and December 31, 2014, consisted of the following (in millions):
		31-Mar-15														31-Dec-14
		Amortized			Fair			Gross Unrealized								Amortized				Fair			Gross Unrealized
		Cost			Value			Gains				Losses				Cost				Value			Gains			Losses
	Fixed maturities:
	U.S. Government and government agencies	$	323		$	330		$	10			$	(3	)		$	347			$	353		$	8		$	(2	)
	States, municipalities and political subdivisions	6,713			7,106			401				(8		)		6,393				6,747			364			(10		)
	Foreign government	172			184			12				—				184				194			10			—
	Residential MBS	3,934			4,325			404				(13		)		4,046				4,442			411			(15		)
	Commercial MBS	2,247			2,403			156				—				2,294				2,451			158			(1		)
	Asset-backed securities	4,175			4,224			57				(8		)		3,872				3,887			37			(22		)
	Corporate and other	12,526			13,396			892				(22		)		11,938				12,660			751			(29		)
	Total fixed maturities	$	30,090		$	31,968		$	1,932			$	(54	)		$	29,074			$	30,734		$	1,739		$	(79	)
	Common stocks	$	888		$	1,087		$	232			$	(33	)		$	885			$	1,087		$	227		$	(25	)
	Perpetual preferred stocks	$	418		$	443		$	28			$	(3	)		$	398			$	414		$	21		$	(5	)
	The non-credit related portion of other-than-temporary impairment charges is included in other comprehensive income. Cumulative non-credit charges taken for securities still owned at March 31, 2015 and December 31, 2014, respectively, were $218 million and $220 million. Gross unrealized gains on such securities at March 31, 2015 and December 31, 2014 were $152 million and $151 million, respectively. Gross unrealized losses on such securities at March 31, 2015 and December 31, 2014 were $7 million and $8 million, respectively. These amounts represent the non-credit other-than-temporary impairment charges recorded in AOCI adjusted for subsequent changes in fair values and nearly all relate to residential MBS.
	The following tables show gross unrealized losses (dollars in millions) on fixed maturities and equity securities by investment category and length of time that individual securities have been in a continuous unrealized loss position at March 31, 2015 and December 31, 2014.
		Less Than Twelve Months									Twelve Months or More
		Unrealized			Fair			Fair Value as			Unrealized				Fair				Fair Value as
		Loss			Value			% of Cost			Loss				Value				% of Cost
	31-Mar-15
	Fixed maturities:
	U.S. Government and government agencies	$	—		$	6		100	%		$	(3	)		$	15			83	%
	States, municipalities and political subdivisions	(5		)	507			99	%		(3		)		57				95	%
	Residential MBS	(5		)	332			99	%		(8		)		193				96	%
	Commercial MBS	—			38			100	%		—				10				100	%
	Asset-backed securities	(3		)	625			100	%		(5		)		461				99	%
	Corporate and other	(18		)	555			97	%		(4		)		75				95	%
	Total fixed maturities	$	(31	)	$	2,063		99	%		$	(23	)		$	811			97	%
	Common stocks	$	(33	)	$	218		87	%		$	—			$	—			—	%
	Perpetual preferred stocks	$	—		$	20		100	%		$	(3	)		$	49			94	%
	31-Dec-14
	Fixed maturities:
	U.S. Government and government agencies	$	—		$	39		100	%		$	(2	)		$	15			88	%
	States, municipalities and political subdivisions	(2		)	222			99	%		(8		)		408				98	%
	Residential MBS	(4		)	298			99	%		(11		)		209				95	%
	Commercial MBS	(1		)	38			97	%		—				11				100	%
	Asset-backed securities	(11		)	1,389			99	%		(11		)		622				98	%
	Corporate and other	(16		)	588			97	%		(13		)		433				97	%
	Total fixed maturities	$	(34	)	$	2,574		99	%		$	(45	)		$	1,698			97	%
	Common stocks	$	(25	)	$	260		91	%		$	—			$	—			—	%
	Perpetual preferred stocks	$	(1	)	$	45		98	%		$	(4	)		$	55			93	%
	At March 31, 2015, the gross unrealized losses on fixed maturities of $54 million relate to approximately 480 securities. Investment grade securities (as determined by nationally recognized rating agencies) represented approximately 55% of the gross unrealized loss and 79% of the fair value.
	AFG analyzes its MBS securities for other-than-temporary impairment each quarter based upon expected future cash flows. Management estimates expected future cash flows based upon its knowledge of the MBS market, cash flow projections (which reflect loan to collateral values, subordination, vintage and geographic concentration) received from independent sources, implied cash flows inherent in security ratings and analysis of historical payment data. In the first three months of 2015, AFG recorded less than $1 million in other-than-temporary impairment charges related to its residential MBS.
	In the first three months of 2015, AFG recorded approximately $5 million in other-than-temporary impairment charges related to corporate bonds.
	AFG recorded $2 million other-than-temporary impairment charges on common stocks in the first three months of 2015. At March 31, 2015, the gross unrealized losses on common stocks of $33 million relate to 33 securities, none of which has been in an unrealized loss position for more than 12 months.
	At March 31, 2015, the gross unrealized losses on preferred stocks of $3 million relate to 11 securities. All of the preferred stocks that have been in an unrealized loss position for 12 months or more (7 securities) have investment grade ratings.
	Management believes AFG will recover its cost basis in the securities with unrealized losses and that AFG has the ability to hold the securities until they recover in value and had no intent to sell them at March 31, 2015.
	A progression of the credit portion of other-than-temporary impairments on fixed maturity securities for which the non-credit portion of an impairment has been recognized in other comprehensive income is shown below (in millions):
		2015			2014
	Balance at January 1	$	170		$	194
	Additional credit impairments on:
	Previously impaired securities	1			—
	Securities without prior impairments	—			—
	Reductions due to sales or redemptions	(3		)	(17		)
	Balance at March 31	$	168		$	177
	The table below sets forth the scheduled maturities of available for sale fixed maturities as of March 31, 2015 (dollars in millions). Securities with sinking funds are reported at average maturity. Actual maturities may differ from contractual maturities because certain securities may be called or prepaid by the issuers.
		Amortized			Fair Value
		Cost			Amount			%
	Maturity
	One year or less	$	958		$	978		3	%
	After one year through five years	4,894			5,262			16	%
	After five years through ten years	9,286			9,817			31	%
After ten years	4,596			4,959			16	%
	19,734			21,016			66	%
ABS (average life of approximately 4-1/2 years)	4,175			4,224			13	%
MBS (average life of approximately 4-1/2 years)	6,181			6,728			21	%
Total	$	30,090		$	31,968		100	%
Certain risks are inherent in connection with fixed maturity securities, including loss upon default, price volatility in reaction to changes in interest rates, and general market factors and risks associated with reinvestment of proceeds due to prepayments or redemptions in a period of declining interest rates.
There were no investments in individual issuers that exceeded 10% of Shareholders’ Equity at March 31, 2015 or December 31, 2014.
Net Unrealized Gain on Marketable Securities   In addition to adjusting equity securities and fixed maturity securities classified as “available for sale” to fair value, GAAP requires that deferred policy acquisition costs and certain other balance sheet amounts related to annuity, long-term care and life businesses be adjusted to the extent that unrealized gains and losses from securities would result in adjustments to those balances had the unrealized gains or losses actually been realized. The following table shows (in millions) the components of the net unrealized gain on securities that is included in AOCI in AFG’s Balance Sheet.
	Pretax			Deferred Tax and			Net
				Amounts
				Attributable
				to Noncontrolling
				Interests
31-Mar-15
Unrealized gain on:
Fixed maturities — annuity segment (*)	$	1,349		$	(472	)	$	877
Fixed maturities — all other	529			(196		)	333
Equity securities	224			(81		)	143
Deferred policy acquisition costs — annuity segment	(601		)	210			(391		)
Annuity benefits accumulated	(179		)	63			(116		)
Life, accident and health reserves	(109		)	38			(71		)
Unearned revenue	36			(12		)	24
	$	1,249		$	(450	)	$	799
31-Dec-14
Unrealized gain on:
Fixed maturities — annuity segment (*)	$	1,157		$	(405	)	$	752
Fixed maturities — all other	503			(185		)	318
Equity securities	218			(79		)	139
Deferred policy acquisition costs — annuity segment	(531		)	186			(345		)
Annuity benefits accumulated	(112		)	39			(73		)
Life, accident and health reserves	(104		)	36			(68		)
Unearned revenue	31			(11		)	20
	$	1,162		$	(419	)	$	743
(*)	Unrealized gains on fixed maturity investments supporting AFG’s annuity benefits accumulated.
Net Investment Income   The following table shows (in millions) investment income earned and investment expenses incurred.
	Three months ended March 31,
	2015			2014
Investment income:
Fixed maturities	$	352		$	327
Equity securities	17			16
Equity in earnings of partnerships and similar investments	3			6
Other	21			17
Gross investment income	393			366
Investment expenses	(5		)	(5		)
Net investment income	$	388		$	361
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments are summarized as follows (in millions):
	Fixed			Equity			Mortgage				Other (a)				Total				Tax			Noncon-			Total
	Maturities			Securities			Loans								Pretax				Effects			trolling
							and Other															Interests
							Investments
Three months ended March 31, 2015
Realized before impairments	$	3		$	21		$	—			$	(1	)		$	23			$	(8	)	$	—		$	15
Realized — impairments	(5		)	(2		)	—				3				(4		)		1			—			(3		)
Change in unrealized	218			6			—				(137		)		87				(30		)	(1		)	56
Three months ended March 31, 2014
Realized before impairments	$	13		$	6		$	1			$	—			$	20			$	(7	)	$	—		$	13
Realized — impairments	(1		)	—			—				—				(1		)		—			—			(1		)
Change in unrealized	316			13			—				(136		)		193				(68		)	(3		)	122
(a)	Primarily adjustments to deferred policy acquisition costs and reserves related to annuities and long-term care business.
Gross realized gains and losses (excluding impairment writedowns and mark-to-market of derivatives) on available for sale fixed maturity and equity security investment transactions included in the Statement of Cash Flows consisted of the following (in millions):
	Three months ended March 31,
	2015			2014
Fixed maturities:
Gross gains	$	5		$	11
Gross losses	—			(1		)
Equity securities:
Gross gains	21			8
Gross losses	—			—

Derivatives

Derivatives	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives	Derivatives
	As discussed under “Derivatives” in Note A — “Accounting Policies” to the financial statements, AFG uses derivatives in certain areas of its operations.
	Derivatives That Do Not Qualify for Hedge Accounting   The following derivatives that do not qualify for hedge accounting under GAAP are included in AFG’s Balance Sheet at fair value (in millions):
			31-Mar-15						31-Dec-14
	Derivative	Balance Sheet Line	Asset			Liability			Asset		Liability
	MBS with embedded derivatives	Fixed maturities	$	164		$	—		$	158	$	—
	Public company warrants	Equity securities	—			—			19		—
	Interest rate swaptions	Other investments	—			—			—		—
	Fixed-indexed annuities (embedded derivative)	Annuity benefits accumulated	—			1,243			—		1,160
	Equity index call options	Other investments	316			—			322		—
	Reinsurance contracts (embedded derivative)	Other liabilities	—			13			—		13
			$	480		$	1,256		$	499	$	1,173
	The MBS with embedded derivatives consist primarily of interest-only MBS with interest rates that float inversely with short-term rates. AFG records the entire change in the fair value of these securities in earnings. These investments are part of AFG’s overall investment strategy and represent a small component of AFG’s investment portfolio.
	Warrants to purchase shares of publicly traded companies, which represent a small component of AFG’s overall investment portfolio, are considered to be derivatives that must be marked to market through earnings. AFG exercised its most significant warrant position in the first three months of 2015.
	AFG has $200 million notional amount of pay-fixed interest rate swaptions (options to enter into pay-fixed/receive floating interest rate swaps at future dates expiring in 2015) outstanding at March 31, 2015, which are used to mitigate interest rate risk in its annuity operations. AFG paid $4 million to purchase these swaptions, which represents its maximum potential economic loss over the life of the contracts.
	AFG’s fixed-indexed annuities, which represented approximately one-half of annuity benefits accumulated at March 31, 2015, provide policyholders with a crediting rate tied, in part, to the performance of an existing stock market index. AFG attempts to mitigate the risk in the index-based component of these products through the purchase of call options on the appropriate index. AFG receives collateral from its counterparties to support its purchased call option assets. This collateral ($262 million at March 31, 2015) is included in other assets in AFG’s Balance Sheet with an offsetting liability to return the collateral, which is included in other liabilities. AFG’s strategy is designed so that an increase in the liabilities, due to an increase in the market index, will be generally offset by unrealized and realized gains on the call options purchased by AFG. Both the index-based component of the annuities and the related call options are considered derivatives. Fluctuations in interest rates and the stock market, among other factors, can cause volatility in the periodic measurement of fair value of the embedded derivative that management believes can be inconsistent with the long-term economics of these products.
	As discussed under “Reinsurance” in Note A to the financial statements, certain reinsurance contracts are considered to contain embedded derivatives.
	The following table summarizes the gain (loss) included in the Statement of Earnings for changes in the fair value of derivatives that do not qualify for hedge accounting for the first three months of 2015 and 2014 (in millions):
			Three months ended March 31,
	Derivative	Statement of Earnings Line	2015			2014
	MBS with embedded derivatives	Realized gains on securities	$	(2	)	$	3
	Public company warrants	Realized gains on securities	—			(2		)
	Interest rate swaptions	Realized gains on securities	—			(1		)
	Fixed-indexed annuities (embedded derivative)	Annuity benefits	(50		)	(54		)
	Equity index call options	Annuity benefits	20			30
	Reinsurance contracts (embedded derivative)	Net investment income	—			(2		)
			$	(32	)	$	(26	)
	Derivatives Designated and Qualifying as Cash Flow Hedges   In the third quarter of 2014, AFG entered into a five-year $431 million notional amount interest rate swap under which AFG receives fixed rate interest payments in exchange for variable interest payments based on one-month LIBOR. The purpose of the swap is to effectively convert a portion of AFG’s floating rate MBS to fixed rate by offsetting the variability in cash flows attributable to changes in one-month LIBOR. The notional amount of the swap amortizes down over its five-year life in anticipation of an expected decline in AFG’s portfolio of MBS with interest rates based on one-month LIBOR ($374 million and $401 million notional amounts at March 31, 2015 and December 31, 2014, respectively). The fair value of the effective portion of the interest rate swap was $2 million and less than $1 million at March 31, 2015 and December 31, 2014, respectively, and is included in AOCI, net of DPAC and tax. During the first three months of 2015, $1 million was reclassified from AOCI to net investment income. There was no ineffectiveness recorded in Net Earnings.

Deferred_Policy_Acquisition_Co

Deferred Policy Acquisition Costs	3 Months Ended
	Mar. 31, 2015
Deferred Policy Acquisition Costs Disclosures [Abstract]
Deferred Policy Acquisition Costs	Deferred Policy Acquisition Costs
	A progression of deferred policy acquisition costs is presented below (in millions):
		P&C			Annuity and Run-off Long-term Care and Life
		Deferred			Deferred			Sales												Consolidated
		Costs			Costs			Inducements			PVFP			Unrealized			Total			Total
	Balance at December 31, 2014	$	221		$	925		$	132		$	74		$	(531	)	$	600		$	821
	Additions	121			44			3			—			—			47			168
	Amortization:
	Periodic amortization	(126		)	(29		)	(7		)	(3		)	—			(39		)	(165		)
	Included in realized gains	—			2			—			—			—			2			2
	Foreign currency translation	1			—			—			—			—			—			1
	Change in unrealized	—			—			—			—			(71		)	(71		)	(71		)
	Balance at March 31, 2015	$	217		$	942		$	128		$	71		$	(602	)	$	539		$	756
	Balance at December 31, 2013	$	211		$	875		$	149		$	85		$	(345	)	$	764		$	975
	Additions	124			50			4			—			—			54			178
	Periodic amortization	(121		)	(27		)	(7		)	(3		)	—			(37		)	(158		)
	Change in unrealized	—			—			—			—			(105		)	(105		)	(105		)
	Balance at March 31, 2014	$	214		$	898		$	146		$	82		$	(450	)	$	676		$	890
	The present value of future profits (“PVFP”) amounts in the table above are net of $212 million and $209 million of accumulated amortization at March 31, 2015 and December 31, 2014, respectively.

Managed_Investment_Entities

Managed Investment Entities	3 Months Ended
	Mar. 31, 2015
Variable Interest Entity, Primary Beneficiary, Does Not Hold Majority Voting Interest, Disclosures [Abstract]
Managed Investment Entities	Managed Investment Entities
	AFG is the investment manager and its subsidiaries have investments ranging from 15.0% to 51.2% of the most subordinate debt tranche of twelve collateralized loan obligation entities or “CLOs,” which are considered variable interest entities. AFG’s subsidiaries also own portions of the senior debt tranches of certain of these CLOs. Upon formation between 2004 and 2014, these entities issued securities in various senior and subordinate classes and invested the proceeds primarily in secured bank loans, which serve as collateral for the debt securities issued by each particular CLO. None of the collateral was purchased from AFG. AFG’s investments in the subordinate debt tranches of these entities receive residual income from the CLOs only after the CLOs pay expenses (including management fees to AFG), and interest on and returns of capital to senior levels of debt securities. There are no contractual requirements for AFG to provide additional funding for these entities. AFG has not provided and does not intend to provide any financial support to these entities.
	AFG’s maximum exposure to economic loss on its CLOs is limited to its investment in the CLOs, which had an aggregate fair value of $325 million (including $127 million invested in the most subordinate debt tranches) at March 31, 2015, and $289 million at December 31, 2014.
	During the first three months of 2014, AFG subsidiaries purchased $3 million face amount of senior debt tranches of existing CLOs for $3 million. During the first three months of 2015 and 2014, AFG subsidiaries received redemption proceeds of $1 million and $29 million, respectively, from its CLO investments.
	The revenues and expenses of the CLOs are separately identified in AFG’s Statement of Earnings, after the elimination of management fees and earnings attributable to shareholders of AFG as measured by the change in the fair value of AFG’s investments in the CLOs. See Note A — “Accounting Policies — Managed Investment Entities,” for a discussion of accounting guidance adopted on January 1, 2015 that impacts the measurement of the fair value of CLO liabilities. Selected financial information related to the CLOs is shown below (in millions):
		Three months ended March 31,
		2015			2014
	Gains (losses) on change in fair value of assets/liabilities (a):
	Assets	$	33		$	(1	)
	Liabilities	(36		)	1
	Management fees paid to AFG	4			3
	CLO earnings attributable to AFG shareholders (b)	3			5
	(a)	Included in Revenues in AFG’s Statement of Earnings.
	(b)	Included in Earnings before income taxes in AFG’s Statement of Earnings.
	The aggregate unpaid principal balance of the CLOs’ fixed maturity investments exceeded the fair value of the investments by $54 million and $83 million at March 31, 2015 and December 31, 2014. The aggregate unpaid principal balance of the CLOs’ debt exceeded its carrying value by $119 million and $131 million at those dates. The CLO assets include $5 million and $2 million in loans (aggregate unpaid principal balance of $10 million and $6 million, respectively) at March 31, 2015 and December 31, 2014 for which the CLOs are not accruing interest because the loans are in default.

Goodwill_and_Other_Intangibles

Goodwill and Other Intangibles	3 Months Ended
	Mar. 31, 2015
Goodwill and Intangible Assets Disclosure [Abstract]
Goodwill and Other Intangibles	Goodwill and Other Intangibles
	There were no changes in the goodwill balance of $201 million during the first three months of 2015. Included in other assets in AFG’s Balance Sheet is $47 million at March 31, 2015 and $49 million at December 31, 2014 in amortizable intangible assets related to property and casualty insurance acquisitions. These amounts are net of accumulated amortization of $12 million and $91 million, respectively. Amortization of intangibles was $2 million and $3 million in the first three months of 2015 and 2014, respectively.

LongTerm_Debt

Long-Term Debt	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Long-Term Debt	Long-Term Debt
	The carrying value of long-term debt consisted of the following (in millions):
		March 31,		December 31,
		2015		2014
	Direct Senior Obligations of AFG:
	9-7/8% Senior Notes due June 2019	$	350	$	350
	6-3/8% Senior Notes due June 2042	230		230
	5-3/4% Senior Notes due August 2042	125		125
	7% Senior Notes due September 2050	132		132
	Other	3		3
		840		840
	Direct Subordinated Obligations of AFG:
	6-1/4% Subordinated Debentures due September 2054	150		150
	Subsidiaries:
	Notes payable secured by real estate due 2015 through 2016	59		59
	National Interstate bank credit facility	12		12
		71		71
		$	1,061	$	1,061
	Scheduled principal payments on debt for the balance of 2015, the subsequent five years and thereafter were as follows: 2015 — $14 million; 2016 — $45 million; 2017 — $12 million; 2018 — none; 2019 — $350 million; 2020 — none and thereafter — $640 million.
	As shown below (in millions), the majority of AFG’s long-term debt is unsecured obligations of the holding company and its subsidiaries:
		March 31,		December 31,
		2015		2014
	Senior unsecured obligations	$	852	$	852
	Subordinated unsecured obligations	150		150
	Obligations secured by real estate	59		59
		$	1,061	$	1,061
	AFG can borrow up to $500 million under its revolving credit facility which expires in December 2016. Amounts borrowed under this agreement bear interest at rates ranging from 1.00% to 1.875% (currently 1.375%) over LIBOR based on AFG’s credit rating. No amounts were borrowed under this facility at March 31, 2015 or December 31, 2014.
	National Interstate can borrow up to $100 million under its unsecured credit agreement, which expires in November 2017. At March 31, 2015, there was $12 million outstanding under this agreement, bearing interest at 1.20% (six-month LIBOR plus 0.875%).

Shareholders_Equity

Shareholders' Equity	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Shareholders' Equity	Shareholders’ Equity
	AFG is authorized to issue 12.5 million shares of Voting Preferred Stock and 12.5 million shares of Nonvoting Preferred Stock, each without par value.
	Accumulated Other Comprehensive Income, Net of Tax (“AOCI”)   Comprehensive income is defined as all changes in Shareholders’ Equity except those arising from transactions with shareholders. Comprehensive income includes net earnings and other comprehensive income, which consists primarily of changes in net unrealized gains or losses on available for sale securities.
	The progression of the components of accumulated other comprehensive income follows (in millions):
					Other Comprehensive Income
		AOCI			Pretax			Tax			Net			Attributable to			Attributable to			AOCI
		Beginning									of			noncontrolling			shareholders			Ending
		Balance									tax			interests						Balance
	Three months ended March 31, 2015
	Net unrealized gains on securities:
	Unrealized holding gains (losses) on securities arising during the period				$	106		$	(37	)	$	69		$	(1	)	$	68
	Reclassification adjustment for realized (gains) losses included in net earnings (a)				(19		)	7			(12		)	—			(12		)
	Total net unrealized gains on securities (b)	$	743		87			(30		)	57			(1		)	56			$	799
	Net unrealized gains on cash flow hedges	—			1			—			1			—			1			1
	Foreign currency translation adjustments	(8		)	(8		)	—			(8		)	—			(8		)	(16		)
	Pension and other postretirement plans adjustments	(8		)	—			—			—			—			—			(8		)
	Total	$	727		$	80		$	(30	)	$	50		$	(1	)	$	49		$	776
	Three months ended March 31, 2014
	Net unrealized gains on securities:
	Unrealized holding gains (losses) on securities arising during the period				$	211		$	(74	)	$	137		$	(3	)	$	134
	Reclassification adjustment for realized (gains) losses included in net earnings (a)				(18		)	6			(12		)	—			(12		)
	Total net unrealized gains on securities	$	563		193			(68		)	125			(3		)	122			$	685
	Foreign currency translation adjustments	1			(5		)	—			(5		)	—			(5		)	(4		)
	Pension and other postretirement plans adjustments	(4		)	—			—			—			—			—			(4		)
	Total	$	560		$	188		$	(68	)	$	120		$	(3	)	$	117		$	677
	(a)	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
	(b)	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.
	Stock Incentive Plans   Under AFG’s stock incentive plans, employees of AFG and its subsidiaries are eligible to receive equity awards in the form of stock options, stock appreciation rights, restricted stock awards, restricted stock units and stock awards. In the first three months of 2015, AFG issued 171,130 shares of restricted Common Stock (fair value of $63.15 per share) and granted stock options for 716,818 shares of Common Stock (at an exercise price of $63.15) under the Stock Incentive Plan. In addition, AFG issued 54,732 shares of Common Stock (fair value of $62.55 per share) in the first quarter of 2015 under the Equity Bonus Plan.
	AFG uses the Black-Scholes option pricing model to calculate the fair value of its option grants. The expected dividend yield is based on AFG’s current dividend rate. To determine expected volatility, AFG considers its daily historical volatility as well as implied volatility on traded options. The expected term was estimated based on historical exercise patterns and post vesting cancellations. The risk-free rate for periods associated with the expected term is based upon the U.S. Treasury yield curve in effect on the grant date.
		Three months ended March 31,
		2015			2014
	Exercise price	$	63.15		$	56.44
	Expected dividend yield	1.6		%	1.6		%
	Expected volatility	25		%	26		%
	Expected term (in years)	7.25			7.25
	Risk-free rate	1.88		%	2.2		%
	Grant date fair value	$	15.29		$	14.65
	Total compensation expense related to stock incentive plans of AFG and its subsidiaries was $6 million and $7 million, respectively, in the first three months of 2015 and 2014.

Income_Taxes

Income Taxes	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes
	The following is a reconciliation of income taxes at the statutory rate of 35% to the provision for income taxes as shown in the Statement of Earnings (dollars in millions):
		Three months ended March 31,
		2015					2014
		Amount			% of EBT		Amount			% of EBT
	Earnings before income taxes (“EBT”)	$	30				$	161
	Income taxes at statutory rate	$	10		35	%	$	56		35	%
	Effect of:
	Tax exempt interest	(7		)	(23	%)	(5		)	(3	%)
	Change in valuation allowance	(1		)	(3	%)	1			1	%
	Subsidiaries not in AFG’s tax return	1			3	%	1			1	%
	Other	2			5	%	1			—	%
	Provision for income taxes as shown in the Statement of Earnings	$	5		17	%	$	54		34	%
	Excluding the tax benefit from the loss on the sale of the long-term care business that was recorded in the first quarter of 2015, AFG’s effective tax rate was 32%. This approximates AFG’s expected annual effective tax rate excluding the loss. During the first three months of 2015, there were no material changes to AFG’s liability for uncertain tax positions.

Contingencies

Contingencies	3 Months Ended
	Mar. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Contingencies	Contingencies
	As discussed in Note B — “Acquisitions and Sale of Businesses,” AFG recorded a $162 million pretax loss in the first quarter of 2015 to establish a liability (included in other liabilities in AFG’s Balance Sheet) that effectively reduces the net carrying value of the assets and liabilities to be disposed in the pending sale of its run-off long-term care business to equal the estimated net sale proceeds from the sale. There have been no significant changes to the matters discussed and referred to in Note M — “Contingencies” of AFG’s 2014 Form 10-K, which covers property and casualty insurance reserves for claims related to environmental exposures, asbestos and other mass tort claims, as well as environmental and occupational injury and disease claims of former subsidiary railroad and manufacturing operations.

Accounting_Policies_Policies

Accounting Policies (Policies)	3 Months Ended
	Mar. 31, 2015
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation   The accompanying consolidated financial statements for American Financial Group, Inc. (“AFG”) and its subsidiaries are unaudited; however, management believes that all adjustments (consisting only of normal recurring accruals unless otherwise disclosed herein) necessary for fair presentation have been made. The results of operations for interim periods are not necessarily indicative of results to be expected for the year. The financial statements have been prepared in accordance with the instructions to Form 10-Q and, therefore, do not include all information and footnotes necessary to be in conformity with U.S. generally accepted accounting principles (“GAAP”).
	Certain reclassifications have been made to prior periods to conform to the current year’s presentation. All significant intercompany balances and transactions have been eliminated. The results of operations of companies since their formation or acquisition are included in the consolidated financial statements. Events or transactions occurring subsequent to March 31, 2015, and prior to the filing of this Form 10-Q, have been evaluated for potential recognition or disclosure herein.
	The preparation of the financial statements requires management to make estimates and assumptions that affect the amounts reported in the financial statements and accompanying notes. Changes in circumstances could cause actual results to differ materially from those estimates.
Fair Value Measurements	Fair Value Measurements   Accounting standards define fair value as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants on the measurement date. The standards establish a hierarchy of valuation techniques based on whether the assumptions that market participants would use in pricing the asset or liability (“inputs”) are observable or unobservable. Observable inputs reflect market data obtained from independent sources, while unobservable inputs reflect AFG’s assumptions about the assumptions market participants would use in pricing the asset or liability. Other than recording an estimated loss on the pending sale of its long-term care business (see Note B — “Acquisitions and Sale of Businesses”), AFG did not have any significant nonrecurring fair value measurements in the first three months of 2015.
Investments	Investments   Fixed maturity and equity securities classified as “available for sale” are reported at fair value with unrealized gains and losses included in accumulated other comprehensive income (“AOCI”) in AFG’s Balance Sheet. Fixed maturity and equity securities classified as “trading” are reported at fair value with changes in unrealized holding gains or losses during the period included in net investment income. Mortgage and policy loans are carried primarily at the aggregate unpaid balance.
	Premiums and discounts on fixed maturity securities are amortized using the interest method; mortgage-backed securities (“MBS”) are amortized over a period based on estimated future principal payments, including prepayments. Prepayment assumptions are reviewed periodically and adjusted to reflect actual prepayments and changes in expectations.
	Gains or losses on securities are determined on the specific identification basis. When a decline in the value of a specific investment is considered to be other-than-temporary at the balance sheet date, a provision for impairment is charged to earnings (included in realized gains (losses) on securities) and the cost basis of that investment is reduced. If management can assert that it does not intend to sell an impaired fixed maturity security and it is not more likely than not that it will have to sell the security before recovery of its amortized cost basis, then the other-than-temporary impairment is separated into two components: (i) the amount related to credit losses (recorded in earnings) and (ii) the amount related to all other factors (recorded in other comprehensive income). The credit-related portion of an other-than-temporary impairment is measured by comparing a security’s amortized cost to the present value of its current expected cash flows discounted at its effective yield prior to the impairment charge. Both components are shown in the Statement of Earnings. If management intends to sell an impaired security, or it is more likely than not that it will be required to sell the security before recovery, an impairment charge to earnings is recorded to reduce the amortized cost of that security to fair value.
Derivatives	Derivatives   Derivatives included in AFG’s Balance Sheet are recorded at fair value. Changes in fair value of derivatives are included in earnings, unless the derivatives are designated as cash flow hedges. Derivatives that do not qualify for hedge accounting under GAAP consist primarily of (i) components of certain fixed maturity securities (primarily interest-only MBS) and (ii) the equity-based component of certain annuity products (included in annuity benefits accumulated) and related call options (included in other investments) designed to be consistent with the characteristics of the liabilities and used to mitigate the risk embedded in those annuity products.
	To qualify for hedge accounting, at the inception of a derivative contract, AFG formally documents the relationship between the terms of the hedge and the hedged items and its risk management objective. This documentation includes defining how hedge effectiveness and ineffectiveness will be measured on a retrospective and prospective basis. Changes in the fair value of derivatives that are designated and qualify as highly effective cash flow hedges are recorded in AOCI and are reclassified into earnings when the variability of the cash flows from the hedged items impact earnings. Any hedge ineffectiveness is immediately recorded in current period earnings. When the change in the fair value of a qualifying cash flow hedge is included in earnings, it is included in the same line item in the Consolidated Statement of Earnings as the cash flows from the hedged item. Qualifying highly effective cash flow hedges include interest rate swaps, which are used to mitigate interest rate risk related to certain floating-rate securities included in AFG’s portfolio of fixed maturity securities.
Goodwill	Goodwill   Goodwill represents the excess of cost of subsidiaries over AFG’s equity in their underlying net assets. Goodwill is not amortized, but is subject to an impairment test at least annually. An entity is not required to complete the quantitative annual goodwill impairment test on a reporting unit if the entity elects to perform a qualitative analysis and determines that it is more likely than not that the reporting unit’s fair value exceeds its carrying amount.
Reinsurance	Reinsurance   Amounts recoverable from reinsurers are estimated in a manner consistent with the claim liability associated with the reinsured policies. AFG’s property and casualty insurance subsidiaries report as assets (i) the estimated reinsurance recoverable on paid and unpaid losses, including an estimate for losses incurred but not reported, and (ii) amounts paid or due to reinsurers applicable to the unexpired terms of policies in force. Payable to reinsurers includes ceded premiums due to reinsurers as well as ceded premiums retained by AFG’s property and casualty insurance subsidiaries under contracts to fund ceded losses as they become due. AFG’s insurance subsidiaries also assume reinsurance from other companies. Earnings on reinsurance assumed is recognized based on information received from ceding companies.
	A subsidiary cedes life insurance policies to a third party on a funds withheld basis whereby the subsidiary retains the assets (securities) associated with the reinsurance contract. Interest is credited to the reinsurer based on the actual investment performance of the retained assets. This reinsurance contract is considered to contain an embedded derivative (that must be adjusted to fair value) because the yield on the payable is based on a specific block of the ceding company’s assets, rather than the overall creditworthiness of the ceding company. AFG determined that changes in the fair value of the underlying portfolio of fixed maturity securities is an appropriate measure of the value of the embedded derivative. The securities related to this contract are classified as “trading.” The adjustment to fair value on the embedded derivative offsets the investment income recorded on the adjustment to fair value of the related trading portfolio.
Deferred Policy Acquisition Costs (DPAC)	Deferred Policy Acquisition Costs (“DPAC”)   Policy acquisition costs (principally commissions, premium taxes and certain underwriting and policy issuance costs) directly related to the successful acquisition or renewal of an insurance contract are deferred. DPAC also includes capitalized costs associated with sales inducements offered to fixed annuity policyholders such as enhanced interest rates and premium and persistency bonuses.
	For the property and casualty companies, DPAC is limited based upon recoverability without any consideration for anticipated investment income and is charged against income ratably over the terms of the related policies. A premium deficiency is recognized if the sum of expected claims costs, claims adjustment expenses and unamortized acquisition costs exceed the related unearned premiums. A premium deficiency is first recognized by charging any unamortized acquisition costs to expense to the extent required to eliminate the deficiency. If the premium deficiency is greater than unamortized acquisition costs, a liability is accrued for the excess deficiency and reported with unpaid losses and loss adjustment expenses.
	DPAC related to annuities is deferred to the extent deemed recoverable and amortized, with interest, in relation to the present value of actual and expected gross profits on the policies. Expected gross profits consist principally of estimated future investment margin (estimated future net investment income less interest credited on policyholder funds) and surrender, mortality, and other life and annuity policy charges, less death, annuitization and guaranteed withdrawal benefits in excess of account balances and estimated future policy administration expenses. To the extent that realized gains and losses result in adjustments to the amortization of DPAC related to annuities, such adjustments are reflected as components of realized gains (losses) on securities.
	DPAC related to traditional life and health insurance is amortized over the expected premium paying period of the related policies, in proportion to the ratio of annual premium revenues to total anticipated premium revenues. See “Life, Accident and Health Reserves” below for details on the impact of loss recognition on the accounting for traditional life and health insurance contracts.
	DPAC includes the present value of future profits on business in force of annuity and life, accident and health insurance companies acquired (“PVFP”). PVFP represents the portion of the costs to acquire companies that is allocated to the value of the right to receive future cash flows from insurance contracts existing at the date of acquisition. PVFP is amortized with interest in relation to expected gross profits of the acquired policies for annuities and universal life products and in relation to the premium paying period for traditional life and health insurance products.
	DPAC and certain other balance sheet amounts related to annuity, long-term care and life businesses are also adjusted, net of tax, for the change in expense that would have been recorded if the unrealized gains (losses) from securities had actually been realized. These adjustments are included in unrealized gains (losses) on marketable securities, a component of AOCI in AFG’s Balance Sheet.
Managed Investment Entities	Managed Investment Entities   A company is considered the primary beneficiary of, and therefore must consolidate, a variable interest entity (“VIE”) based primarily on its ability to direct the activities of the VIE that most significantly impact that entity’s economic performance and the obligation to absorb losses of, or receive benefits from, the entity that could potentially be significant to the VIE.
	AFG manages, and has investments in, collateralized loan obligations (“CLOs”) that are VIEs (see Note H — “Managed Investment Entities”). Both the management fees (payment of which is subordinate to other obligations of the CLOs) and the investments in the CLOs are considered variable interests. AFG has determined that it is the primary beneficiary of the CLOs because (i) its role as asset manager gives it the power to direct the activities that most significantly impact the economic performance of the CLOs and (ii) it has exposure to CLO losses (through its investments in the CLO debt tranches) and the right to receive benefits (through its subordinated management fees and returns on its investments), both of which could potentially be significant to the CLOs.
	In February 2015, the Financial Accounting Standards Board issued Accounting Standards Update (“ASU”) 2015-02, which amends certain consolidation accounting guidance, including the VIE guidance that applies to collateralized financing entities such as CLOs. The new guidance, which AFG intends to adopt effective January 1, 2016, will affect how fee arrangements with CLO asset managers impact the determination of the primary beneficiary of these entities. Due to the significance of AFG’s investments in the CLOs that it manages, management does not expect the new guidance to impact the consolidation of its currently outstanding CLOs. In addition, the new guidance impacts the consolidation analysis that applies to limited partnerships and similar entities. Management is currently evaluating its investments in limited partnerships and similar entities under the new guidance.
	Because AFG has no right to use the CLO assets and no obligation to pay the CLO liabilities, the assets and liabilities of the CLOs are shown separately in AFG’s Balance Sheet. AFG has elected the fair value option for reporting on the CLO assets and liabilities to improve the transparency of financial reporting related to the CLOs. The net gain or loss from accounting for the CLO assets and liabilities at fair value is presented separately in AFG’s Statement of Earnings.
	Effective January 1, 2015, AFG adopted (on a modified retrospective basis) ASU 2014-13, which addresses the diversity in practice regarding the accounting for assets and liabilities of a consolidated collateralized financing entity (such as a CLO) when an election has been made to account for that entity’s assets and liabilities at fair value. The fair values of a CLO’s assets may differ from the separately measured fair values of its liabilities even though the CLO liabilities only have recourse to the CLO assets. Under the new guidance, AFG has elected to set the carrying value of the CLO liabilities equal to the fair value of the CLO assets (which have more observable fair values) as an alternative to reporting those liabilities at a separately measured fair value. CLO earnings attributable to AFG’s shareholders continue to be measured by the change in the fair value of AFG’s investments in the CLOs and management fees earned.
	Prior to the adoption of this guidance, measuring both the CLO assets and CLO liabilities at separately determined fair values resulted in a difference between the carrying value of the CLO assets and the carrying value of the CLO liabilities that was not attributable to AFG’s ownership interest in the CLOs and CLO earnings (losses) that were not attributable to AFG’s shareholders. Accordingly, in periods prior to 2015, the difference between the fair value of the CLO assets and the fair value of the CLO liabilities was recorded as “appropriated retained earnings — managed investment entities” in AFG’s Balance Sheet and the earnings (losses) that were not attributable to AFG’s shareholders were included in net earnings (loss) attributable to noncontrolling interests in AFG’s Statement of Earnings.
	Under the guidance adopted in 2015, there is no longer any excess carrying value of CLO assets over the carrying value of CLO liabilities to be reported as “appropriated retained earnings — managed investment entities” in AFG’s Balance Sheet or any CLO earnings to be attributed to noncontrolling interests in AFG’s Statement of Earnings. In accordance with the guidance, the amount reported as “appropriated retained earnings — managed investment entities” at December 31, 2014 was reclassified to “liabilities of managed investment entities” on January 1, 2015 as the cumulative effect of an accounting change. While the new guidance impacted the presentation of individual CLO-related line items in AFG’s Statement of Earnings, it had no overall impact on AFG’s Net Earnings Attributable to Shareholders.
	At March 31, 2015, assets and liabilities of managed investment entities included $222 million in assets and $177 million in liabilities of a temporary warehousing entity that was established in connection with the formation of a new CLO that is expected to close in the second quarter of 2015. Upon closing, all warehoused assets are expected to be transferred to the new CLO and the liabilities will be repaid.
Unpaid Losses and Loss Adjustment Expenses	Unpaid Losses and Loss Adjustment Expenses   The net liabilities stated for unpaid claims and for expenses of investigation and adjustment of unpaid claims represent management’s best estimate and are based upon (i) the accumulation of case estimates for losses reported prior to the close of the accounting period on direct business written; (ii) estimates received from ceding reinsurers and insurance pools and associations; (iii) estimates of unreported losses (including possible development on known claims) based on past experience; (iv) estimates based on experience of expenses for investigating and adjusting claims; and (v) the current state of the law and coverage litigation. Establishing reserves for asbestos, environmental and other mass tort claims involves considerably more judgment than other types of claims due to, among other things, inconsistent court decisions, an increase in bankruptcy filings as a result of asbestos-related liabilities, novel theories of coverage, and judicial interpretations that often expand theories of recovery and broaden the scope of coverage.
	Loss reserve liabilities are subject to the impact of changes in claim amounts and frequency and other factors. Changes in estimates of the liabilities for losses and loss adjustment expenses are reflected in the Statement of Earnings in the period in which determined. Despite the variability inherent in such estimates, management believes that the liabilities for unpaid losses and loss adjustment expenses are adequate.
Annuity Benefits Accumulated	Annuity Benefits Accumulated   Annuity receipts and benefit payments are recorded as increases or decreases in annuity benefits accumulated rather than as revenue and expense. Increases in this liability for interest credited are charged to expense and decreases for policy charges are credited to other income.
	For certain products, annuity benefits accumulated also includes reserves for accrued persistency and premium bonuses, guaranteed withdrawals and excess benefits expected to be paid on future deaths and annuitizations (“EDAR”). The liabilities for EDAR and guaranteed withdrawals are accrued for and modified using assumptions consistent with those used in determining DPAC and DPAC amortization, except that amounts are determined in relation to the present value of total expected assessments. Total expected assessments consist principally of estimated future investment margin, surrender, mortality, and other life and annuity policy charges, and unearned revenues once they are recognized as income.
	Annuity benefits accumulated also includes amounts advanced from the Federal Home Loan Bank of Cincinnati.
Unearned Revenue	Unearned Revenue   Certain upfront policy charges on annuities are deferred as unearned revenue (included in other liabilities) and recognized in net earnings using the same assumptions and estimated gross profits used to amortize DPAC.
Life, Accident and Health Reserves	Life, Accident and Health Reserves   Liabilities for future policy benefits under traditional life, accident and health policies are computed using the net level premium method. Computations are based on the original projections of investment yields, mortality, morbidity and surrenders and include provisions for unfavorable deviations unless a loss recognition event (premium deficiency) occurs. Claim reserves and liabilities established for accident and health claims are modified as necessary to reflect actual experience and developing trends.
	For long-duration contracts (such as traditional life and long-term care policies), loss recognition occurs when, based on current expectations as of the measurement date, existing contract liabilities plus the present value of future premiums (including reasonably expected rate increases) are not expected to cover the present value of future claims payments and related settlement and maintenance costs (excluding overhead) as well as unamortized acquisition costs. If a block of business is determined to be in loss recognition, a charge is recorded in earnings in an amount equal to the excess of the present value of expected future claims costs and unamortized acquisition costs over existing reserves plus the present value of expected future premiums (with no provision for adverse deviation). The charge is recorded first to reduce unamortized acquisition costs and then as an additional reserve (if unamortized acquisition costs have been reduced to zero).
	In addition, reserves for traditional life and long-term care policies are subject to adjustment for loss recognition charges that would have been recorded if the unrealized gains from securities had actually been realized. This adjustment is included in unrealized gains (losses) on marketable securities, a component of AOCI in AFG’s Balance Sheet.
Variable Annuity Assets and Liabilities	Variable Annuity Assets and Liabilities   Separate accounts related to variable annuities represent the fair value of deposits invested in underlying investment funds on which AFG earns a fee. Investment funds are selected and may be changed only by the policyholder, who retains all investment risk.
	AFG’s variable annuity contracts contain a guaranteed minimum death benefit (“GMDB”) to be paid if the policyholder dies before the annuity payout period commences. In periods of declining equity markets, the GMDB may exceed the value of the policyholder’s account. A GMDB liability is established for future excess death benefits using assumptions together with a range of reasonably possible scenarios for investment fund performance that are consistent with DPAC capitalization and amortization assumptions.
Premium Recognition	Premium Recognition   Property and casualty premiums are earned generally over the terms of the policies on a pro rata basis. Unearned premiums represent that portion of premiums written which is applicable to the unexpired terms of policies in force. On reinsurance assumed from other insurance companies or written through various underwriting organizations, unearned premiums are based on information received from such companies and organizations. For traditional life, accident and health products, premiums are recognized as revenue when legally collectible from policyholders. For interest-sensitive life and universal life products, premiums are recorded in a policyholder account, which is reflected as a liability. Revenue is recognized as amounts are assessed against the policyholder account for mortality coverage and contract expenses.
Noncontrolling Interests	Noncontrolling Interests   For Balance Sheet purposes, noncontrolling interests represents the interests of shareholders other than AFG in consolidated entities. In the Statement of Earnings, net earnings and losses attributable to noncontrolling interests represents such shareholders’ interest in the earnings and losses of those entities.
Income Taxes	Income Taxes   Deferred income taxes are calculated using the liability method. Under this method, deferred income tax assets and liabilities are determined based on differences between financial reporting and tax bases and are measured using enacted tax rates. A valuation allowance is established to reduce total deferred tax assets to an amount that will more likely than not be realized.
	AFG recognizes the tax benefits of uncertain tax positions only when the position is more likely than not to be sustained under examination by the appropriate taxing authority. Interest and penalties on AFG’s reserve for uncertain tax positions are recognized as a component of tax expense.
Stock-Based Compensation	Stock-Based Compensation   All share-based grants are recognized as compensation expense on a straight-line basis over their vesting periods based on their calculated fair value at the date of grant. AFG uses the Black-Scholes pricing model to measure the fair value of employee stock options. See Note K — “Shareholders’ Equity” for further information.
Benefit Plans	Benefit Plans   AFG provides retirement benefits to qualified employees of participating companies through the AFG 401(k) Retirement and Savings Plan, a defined contribution plan. AFG makes all contributions to the retirement fund portion of the plan and matches a percentage of employee contributions to the savings fund. Company contributions are expensed in the year for which they are declared. AFG and many of its subsidiaries provide health care and life insurance benefits to eligible retirees. AFG also provides postemployment benefits to former or inactive employees (primarily those on disability) who were not deemed retired under other company plans. The projected future cost of providing these benefits is expensed over the period employees earn such benefits.
Earnings Per Share	Earnings Per Share   Although basic earnings per share only considers shares of common stock outstanding during the period, the calculation of diluted earnings per share includes the following adjustments to weighted average common shares related to stock-based compensation plans: first three months of 2015 and 2014 — 1.8 million and 2.0 million, respectively.
	AFG’s weighted average diluted shares outstanding excludes the following anti-dilutive potential common shares related to stock compensation plans: first three months of 2015 and 2014 — 1.3 million and 0.6 million, respectively. Adjustments to net earnings attributable to shareholders in the calculation of diluted earnings per share were nominal in the 2015 and 2014 periods.
Statement of Cash Flows	Statement of Cash Flows   For cash flow purposes, “investing activities” are defined as making and collecting loans and acquiring and disposing of debt or equity instruments and property and equipment. “Financing activities” include obtaining resources from owners and providing them with a return on their investments, borrowing money and repaying amounts borrowed. Annuity receipts, surrenders, benefits and withdrawals are also reflected as financing activities. All other activities are considered “operating.” Short-term investments having original maturities of three months or less when purchased are considered to be cash equivalents for purposes of the financial statements.

Acquisitions_and_Sale_of_Busin1

Acquisitions and Sale of Businesses (Tables)	3 Months Ended
	Mar. 31, 2015
Business Combinations [Abstract]
Summarized financial information	The estimated impact of the third quarter sale of the run-off long-term care insurance business on AFG’s financial statements is shown below (in millions):
		March 31, 2015
	Estimated sale proceeds (*)	$	14
	Assets of businesses sold:
	Cash and investments	$	1,397
	Recoverables from reinsurers	603
	Deferred policy acquisition costs	15
	Other receivables	14
	Other assets	7
	Goodwill	2
	Total assets	2,038
	Liabilities of businesses sold:
	Annuity benefits accumulated	270
	Life, accident and health reserves	1,537
	Other liabilities	27
	Total liabilities	1,834
	Reclassify net unrealized gain on marketable securities	28
	Net assets of businesses sold	$	176
	Pretax loss on subsidiaries	$	(162	)
	(*)	Includes fair value of the potential additional consideration and is shown net of estimated expenses.
	Revenues, costs and expenses, and earnings before income taxes for the subsidiaries to be sold were (in millions):
		Three months ended March 31,
		2015			2014
	Life, accident and health net earned premiums:
	Long-term care	$	17		$	19
	Life operations	3			3
	Net investment income	18			21
	Realized gains (losses) on securities and other income	(2		)	1
	Total revenues	36			44
	Annuity benefits	2			2
	Life, accident and health benefits:
	Long-term care	21			29
	Life operations	3			3
	Annuity and supplemental insurance acquisition expenses	3			3
	Other expenses	4			4
	Total costs and expenses	33			41
	Earnings before income taxes	$	3		$	3

Segments_of_Operations_Tables

Segments of Operations (Tables)	3 Months Ended
	Mar. 31, 2015
Segment Reporting [Abstract]
Segment Reporting Information, by Segment	The following tables (in millions) show AFG’s revenues and earnings before income taxes by segment and sub-segment.
		Three months ended March 31,
		2015			2014
	Revenues
	Property and casualty insurance:
	Premiums earned:
	Specialty
	Property and transportation	$	313		$	301
	Specialty casualty	490			313
	Specialty financial	120			117
	Other specialty	23			23
	Total premiums earned	946			754
	Net investment income	79			67
	Other income	6			2
	Total property and casualty insurance	1,031			823
	Annuity:
	Net investment income	292			275
	Other income	24			18
	Total annuity	316			293
	Run-off long-term care and life	46			51
	Other	44			25
	Total revenues before realized gains (loss)	1,437			1,192
	Realized gains on securities	19			19
	Realized loss on subsidiaries	(162		)	—
	Total revenues	$	1,294		$	1,211
		Three months ended March 31,
		2015			2014
	Earnings Before Income Taxes
	Property and casualty insurance:
	Underwriting:
	Specialty
	Property and transportation	$	7		$	6
	Specialty casualty	28			38
	Specialty financial	22			10
	Other specialty	3			5
	Other lines	—			(1		)
	Total underwriting	60			58
	Investment and other income, net	73			54
	Total property and casualty insurance	133			112
	Annuity	75			73
	Run-off long-term care and life	4			(2		)
	Other (*)	(39		)	(41		)
	Total earnings before realized gains (loss) and income taxes	173			142
	Realized gains on securities	19			19
	Realized loss on subsidiaries	(162		)	—
	Total earnings before income taxes	$	30		$	161
	(*)	Includes holding company expenses. Also includes earnings of managed investment entities attributable to noncontrolling interest of less than $1 million for the first three months of 2014. Following the adoption of new guidance in the first quarter of 2015, there are no longer earnings of managed investment entities that are attributable to noncontrolling interests. See Note A — “Accounting Policies — Managed Investment Entities.”

Fair_Value_Measurements_Tables

Fair Value Measurements (Tables)	3 Months Ended
	Mar. 31, 2015
Fair Value Disclosures [Abstract]
Assets and liabilities measured at fair value	Assets and liabilities measured and carried at fair value in the financial statements are summarized below (in millions):
		Level 1			Level 2			Level 3			Total
	31-Mar-15
	Assets:
	Available for sale (“AFS”) fixed maturities:
	U.S. Government and government agencies	$	123		$	192		$	15		$	330
	States, municipalities and political subdivisions	—			7,045			61			7,106
	Foreign government	—			184			—			184
	Residential MBS	—			4,019			306			4,325
	Commercial MBS	—			2,359			44			2,403
	Asset-backed securities (“ABS”)	—			4,013			211			4,224
	Corporate and other	38			12,775			583			13,396
	Total AFS fixed maturities	161			30,587			1,220			31,968
	Trading fixed maturities	13			260			—			273
	Equity securities	1,388			238			84			1,710
	Assets of managed investment entities (“MIE”)	120			3,130			29			3,279
	Variable annuity assets (separate accounts) (*)	—			667			—			667
	Other investments — derivatives	—			318			—			318
	Total assets accounted for at fair value	$	1,682		$	35,200		$	1,333		$	38,215
	Liabilities:
	Liabilities of managed investment entities	$	108		$	2,818		$	26		$	2,952
	Derivatives in annuity benefits accumulated	—			—			1,243			1,243
	Other liabilities — derivatives	—			13			—			13
	Total liabilities accounted for at fair value	$	108		$	2,831		$	1,269		$	4,208
	31-Dec-14
	Assets:
	Available for sale fixed maturities:
	U.S. Government and government agencies	$	164		$	174		$	15		$	353
	States, municipalities and political subdivisions	—			6,647			100			6,747
	Foreign government	—			194			—			194
	Residential MBS	—			4,142			300			4,442
	Commercial MBS	—			2,407			44			2,451
	Asset-backed securities	—			3,661			226			3,887
	Corporate and other	36			12,078			546			12,660
	Total AFS fixed maturities	200			29,303			1,231			30,734
	Trading fixed maturities	12			254			—			266
	Equity securities	1,306			297			93			1,696
	Assets of managed investment entities	174			2,903			31			3,108
	Variable annuity assets (separate accounts) (*)	—			662			—			662
	Other investments — derivatives	—			322			—			322
	Total assets accounted for at fair value	$	1,692		$	33,741		$	1,355		$	36,788
	Liabilities:
	Liabilities of managed investment entities	$	118		$	—		$	2,701		$	2,819
	Derivatives in annuity benefits accumulated	—			—			1,160			1,160
	Other liabilities — derivatives	—			13			—			13
	Total liabilities accounted for at fair value	$	118		$	13		$	3,861		$	3,992
	(*)    Variable annuity liabilities equal the fair value of variable annuity assets.
Unobservable inputs used by management in determining fair value of embedded derivatives	The following table presents information about the unobservable inputs used by management in determining fair value of these embedded derivatives. See Note F — “Derivatives.”
	Unobservable Input		Range
	Adjustment for insurance subsidiary’s credit risk		0.40% – 1.75% over the risk free rate
	Risk margin for uncertainty in cash flows		0.52% reduction in the discount rate
	Surrenders		4% – 16% of indexed account value
	Partial surrenders		2% – 10% of indexed account value
	Annuitizations		1% – 1.5% of indexed account value
	Deaths		1.5% – 3.0% of indexed account value
	Budgeted option costs		2.0% – 3.25% of indexed account value
Changes in balances of Level 3 financial assets and liabilities	Changes in balances of Level 3 financial assets and liabilities carried at fair value during the first three months of 2015 and 2014 are presented below (in millions). The transfers into and out of Level 3 were due to changes in the availability of market observable inputs. All transfers are reflected in the table at fair value as of the end of the reporting period.
								Total realized/unrealized
								gains (losses) included in
		Balance at December 31, 2014			Impact of			Net			Other			Purchases			Sales and			Transfer			Transfer			Balance at March 31, 2015
					accounting			income			comprehensive			and			settlements			into			out of
					change (*)						income (loss)			issuances						Level 3			Level 3
	AFS fixed maturities:
	U.S. government agency	$	15		$	—		$	—		$	—		$	—		$	—		$	—		$	—		$	15
	State and municipal	100			—			—			—			—			—			—			(39		)	61
	Residential MBS	300			—			(1		)	3			—			(7		)	41			(30		)	306
	Commercial MBS	44			—			—			—			—			—			—			—			44
	Asset-backed securities	226			—			—			—			5			(41		)	21			—			211
	Corporate and other	546			—			—			6			44			(13		)	—			—			583
	Equity securities	93			—			—			(2		)	10			—			—			(17		)	84
	Assets of MIE	31			—			(2		)	—			—			—			—			—			29
	Liabilities of MIE	(2,701		)	2,701			—			—			—			—			—			—			—
	Embedded derivatives	(1,160		)	—			(50		)	—			(47		)	14			—			—			(1,243		)
	(*)	The impact of implementing new guidance adopted in 2015, as discussed above and in Note A — “Accounting Policies — Managed Investment Entities.”
					Total realized/unrealized
					gains (losses) included in
		Balance at December 31, 2013			Net			Other			Purchases			Sales and			Transfer			Transfer			Balance at March 31, 2014
					income			comprehensive			and			settlements			into			out of
								income (loss)			issuances						Level 3			Level 3
	AFS fixed maturities:
	U.S. government agency	$	15		$	—		$	—		$	—		$	—		$	—		$	—		$	15
	State and municipal	61			—			—			—			—			—			—			61
	Residential MBS	316			1			4			—			(8		)	32			(73		)	272
	Commercial MBS	28			—			—			—			—			—			—			28
	Asset-backed securities	75			—			1			50			(1		)	81			—			206
	Corporate and other	335			1			3			1			(16		)	—			(2		)	322
	Equity securities	31			1			2			30			(9		)	—			(14		)	41
	Assets of MIE	30			(1		)	—			—			—			—			—			29
	Liabilities of MIE (*)	(2,411		)	1			—			(45		)	133			—			—			(2,322		)
	Embedded derivatives	(804		)	(54		)	—			(55		)	9			—			—			(904		)
	(*)	Total realized/unrealized gains (losses) included in net income includes gains of $4 million related to liabilities outstanding as of March 31, 2014. See Note H — “Managed Investment Entities.”
Fair value of financial instruments	The carrying value and fair value of financial instruments that are not carried at fair value in the financial statements are summarized below (in millions):
		Carrying			Fair			Level 1			Level 2			Level 3
		Value			Value
	31-Mar-15
	Financial assets:
	Cash and cash equivalents	$	1,212		$	1,212		$	1,212		$	—		$	—
	Mortgage loans	1,091			1,100			—			—			1,100
	Policy loans	226			226			—			—			226
	Total financial assets not accounted for at fair value	$	2,529		$	2,538		$	1,212		$	—		$	1,326
	Financial liabilities:
	Annuity benefits accumulated (*)	$	24,209		$	23,966		$	—		$	—		$	23,966
	Long-term debt	1,061			1,197			—			1,123			74
	Total financial liabilities not accounted for at fair value	$	25,270		$	25,163		$	—		$	1,123		$	24,040
	31-Dec-14
	Financial assets:
	Cash and cash equivalents	$	1,343		$	1,343		$	1,343		$	—		$	—
	Mortgage loans	1,117			1,124			—			—			1,124
	Policy loans	228			228			—			—			228
	Total financial assets not accounted for at fair value	$	2,688		$	2,695		$	1,343		$	—		$	1,352
	Financial liabilities:
	Annuity benefits accumulated (*)	$	23,561		$	23,187		$	—		$	—		$	23,187
	Long-term debt	1,061			1,180			—			1,106			74
	Total financial liabilities not accounted for at fair value	$	24,622		$	24,367		$	—		$	1,106		$	23,261
	(*)	Excludes life contingent annuities in the payout phase.

Investments_Tables

Investments (Tables)	3 Months Ended
	Mar. 31, 2015
Investments, Debt and Equity Securities [Abstract]
Available for sale fixed maturities and equity securities	Available for sale fixed maturities and equity securities at March 31, 2015 and December 31, 2014, consisted of the following (in millions):
		31-Mar-15														31-Dec-14
		Amortized			Fair			Gross Unrealized								Amortized				Fair			Gross Unrealized
		Cost			Value			Gains				Losses				Cost				Value			Gains			Losses
	Fixed maturities:
	U.S. Government and government agencies	$	323		$	330		$	10			$	(3	)		$	347			$	353		$	8		$	(2	)
	States, municipalities and political subdivisions	6,713			7,106			401				(8		)		6,393				6,747			364			(10		)
	Foreign government	172			184			12				—				184				194			10			—
	Residential MBS	3,934			4,325			404				(13		)		4,046				4,442			411			(15		)
	Commercial MBS	2,247			2,403			156				—				2,294				2,451			158			(1		)
	Asset-backed securities	4,175			4,224			57				(8		)		3,872				3,887			37			(22		)
	Corporate and other	12,526			13,396			892				(22		)		11,938				12,660			751			(29		)
	Total fixed maturities	$	30,090		$	31,968		$	1,932			$	(54	)		$	29,074			$	30,734		$	1,739		$	(79	)
	Common stocks	$	888		$	1,087		$	232			$	(33	)		$	885			$	1,087		$	227		$	(25	)
	Perpetual preferred stocks	$	418		$	443		$	28			$	(3	)		$	398			$	414		$	21		$	(5	)
Available for sale securities in a continuous unrealized loss position	The following tables show gross unrealized losses (dollars in millions) on fixed maturities and equity securities by investment category and length of time that individual securities have been in a continuous unrealized loss position at March 31, 2015 and December 31, 2014.
		Less Than Twelve Months									Twelve Months or More
		Unrealized			Fair			Fair Value as			Unrealized				Fair				Fair Value as
		Loss			Value			% of Cost			Loss				Value				% of Cost
	31-Mar-15
	Fixed maturities:
	U.S. Government and government agencies	$	—		$	6		100	%		$	(3	)		$	15			83	%
	States, municipalities and political subdivisions	(5		)	507			99	%		(3		)		57				95	%
	Residential MBS	(5		)	332			99	%		(8		)		193				96	%
	Commercial MBS	—			38			100	%		—				10				100	%
	Asset-backed securities	(3		)	625			100	%		(5		)		461				99	%
	Corporate and other	(18		)	555			97	%		(4		)		75				95	%
	Total fixed maturities	$	(31	)	$	2,063		99	%		$	(23	)		$	811			97	%
	Common stocks	$	(33	)	$	218		87	%		$	—			$	—			—	%
	Perpetual preferred stocks	$	—		$	20		100	%		$	(3	)		$	49			94	%
	31-Dec-14
	Fixed maturities:
	U.S. Government and government agencies	$	—		$	39		100	%		$	(2	)		$	15			88	%
	States, municipalities and political subdivisions	(2		)	222			99	%		(8		)		408				98	%
	Residential MBS	(4		)	298			99	%		(11		)		209				95	%
	Commercial MBS	(1		)	38			97	%		—				11				100	%
	Asset-backed securities	(11		)	1,389			99	%		(11		)		622				98	%
	Corporate and other	(16		)	588			97	%		(13		)		433				97	%
	Total fixed maturities	$	(34	)	$	2,574		99	%		$	(45	)		$	1,698			97	%
	Common stocks	$	(25	)	$	260		91	%		$	—			$	—			—	%
	Perpetual preferred stocks	$	(1	)	$	45		98	%		$	(4	)		$	55			93	%
Roll forward of cumulative credit portion of other-than-temporary impairments on fixed maturity securities	A progression of the credit portion of other-than-temporary impairments on fixed maturity securities for which the non-credit portion of an impairment has been recognized in other comprehensive income is shown below (in millions):
		2015			2014
	Balance at January 1	$	170		$	194
	Additional credit impairments on:
	Previously impaired securities	1			—
	Securities without prior impairments	—			—
	Reductions due to sales or redemptions	(3		)	(17		)
	Balance at March 31	$	168		$	177
Available for sale fixed maturity securities by contractual maturity date	The table below sets forth the scheduled maturities of available for sale fixed maturities as of March 31, 2015 (dollars in millions). Securities with sinking funds are reported at average maturity. Actual maturities may differ from contractual maturities because certain securities may be called or prepaid by the issuers.
		Amortized			Fair Value
		Cost			Amount			%
	Maturity
	One year or less	$	958		$	978		3	%
	After one year through five years	4,894			5,262			16	%
	After five years through ten years	9,286			9,817			31	%
	After ten years	4,596			4,959			16	%
		19,734			21,016			66	%
	ABS (average life of approximately 4-1/2 years)	4,175			4,224			13	%
	MBS (average life of approximately 4-1/2 years)	6,181			6,728			21	%
	Total	$	30,090		$	31,968		100	%
Components of the net unrealized gain on securities, included in Accumulated Other Comprehensive Income	The following table shows (in millions) the components of the net unrealized gain on securities that is included in AOCI in AFG’s Balance Sheet.
		Pretax			Deferred Tax and			Net
					Amounts
					Attributable
					to Noncontrolling
					Interests
	31-Mar-15
	Unrealized gain on:
	Fixed maturities — annuity segment (*)	$	1,349		$	(472	)	$	877
	Fixed maturities — all other	529			(196		)	333
	Equity securities	224			(81		)	143
	Deferred policy acquisition costs — annuity segment	(601		)	210			(391		)
	Annuity benefits accumulated	(179		)	63			(116		)
	Life, accident and health reserves	(109		)	38			(71		)
	Unearned revenue	36			(12		)	24
		$	1,249		$	(450	)	$	799
	31-Dec-14
	Unrealized gain on:
	Fixed maturities — annuity segment (*)	$	1,157		$	(405	)	$	752
	Fixed maturities — all other	503			(185		)	318
	Equity securities	218			(79		)	139
	Deferred policy acquisition costs — annuity segment	(531		)	186			(345		)
	Annuity benefits accumulated	(112		)	39			(73		)
	Life, accident and health reserves	(104		)	36			(68		)
	Unearned revenue	31			(11		)	20
		$	1,162		$	(419	)	$	743
	(*)	Unrealized gains on fixed maturity investments supporting AFG’s annuity benefits accumulated.
Net investment income earned and investment expenses incurred	The following table shows (in millions) investment income earned and investment expenses incurred.
		Three months ended March 31,
		2015			2014
	Investment income:
	Fixed maturities	$	352		$	327
	Equity securities	17			16
	Equity in earnings of partnerships and similar investments	3			6
	Other	21			17
	Gross investment income	393			366
	Investment expenses	(5		)	(5		)
	Net investment income	$	388		$	361
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments	Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments are summarized as follows (in millions):
		Fixed			Equity			Mortgage				Other (a)				Total				Tax			Noncon-			Total
		Maturities			Securities			Loans								Pretax				Effects			trolling
								and Other															Interests
								Investments
	Three months ended March 31, 2015
	Realized before impairments	$	3		$	21		$	—			$	(1	)		$	23			$	(8	)	$	—		$	15
	Realized — impairments	(5		)	(2		)	—				3				(4		)		1			—			(3		)
	Change in unrealized	218			6			—				(137		)		87				(30		)	(1		)	56
	Three months ended March 31, 2014
	Realized before impairments	$	13		$	6		$	1			$	—			$	20			$	(7	)	$	—		$	13
	Realized — impairments	(1		)	—			—				—				(1		)		—			—			(1		)
	Change in unrealized	316			13			—				(136		)		193				(68		)	(3		)	122
	(a)	Primarily adjustments to deferred policy acquisition costs and reserves related to annuities and long-term care business.
Gross realized gains and losses on available for sale fixed maturity and equity security investments	Gross realized gains and losses (excluding impairment writedowns and mark-to-market of derivatives) on available for sale fixed maturity and equity security investment transactions included in the Statement of Cash Flows consisted of the following (in millions):
		Three months ended March 31,
		2015			2014
	Fixed maturities:
	Gross gains	$	5		$	11
	Gross losses	—			(1		)
	Equity securities:
	Gross gains	21			8
	Gross losses	—			—

Derivatives_Tables

Derivatives (Tables)	3 Months Ended
	Mar. 31, 2015
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivatives included in Balance Sheet at fair value	The following derivatives that do not qualify for hedge accounting under GAAP are included in AFG’s Balance Sheet at fair value (in millions):
			31-Mar-15						31-Dec-14
	Derivative	Balance Sheet Line	Asset			Liability			Asset		Liability
	MBS with embedded derivatives	Fixed maturities	$	164		$	—		$	158	$	—
	Public company warrants	Equity securities	—			—			19		—
	Interest rate swaptions	Other investments	—			—			—		—
	Fixed-indexed annuities (embedded derivative)	Annuity benefits accumulated	—			1,243			—		1,160
	Equity index call options	Other investments	316			—			322		—
	Reinsurance contracts (embedded derivative)	Other liabilities	—			13			—		13
			$	480		$	1,256		$	499	$	1,173
Summary of gain (loss) included in the Statement of Earnings for changes in the fair value of derivatives	The following table summarizes the gain (loss) included in the Statement of Earnings for changes in the fair value of derivatives that do not qualify for hedge accounting for the first three months of 2015 and 2014 (in millions):
			Three months ended March 31,
	Derivative	Statement of Earnings Line	2015			2014
	MBS with embedded derivatives	Realized gains on securities	$	(2	)	$	3
	Public company warrants	Realized gains on securities	—			(2		)
	Interest rate swaptions	Realized gains on securities	—			(1		)
	Fixed-indexed annuities (embedded derivative)	Annuity benefits	(50		)	(54		)
	Equity index call options	Annuity benefits	20			30
	Reinsurance contracts (embedded derivative)	Net investment income	—			(2		)
			$	(32	)	$	(26	)

Deferred_Policy_Acquisition_Co1

Deferred Policy Acquisition Costs (Tables)	3 Months Ended
	Mar. 31, 2015
Deferred Policy Acquisition Costs Disclosures [Abstract]
Deferred Policy Acquisition Costs Details	A progression of deferred policy acquisition costs is presented below (in millions):
		P&C			Annuity and Run-off Long-term Care and Life
		Deferred			Deferred			Sales												Consolidated
		Costs			Costs			Inducements			PVFP			Unrealized			Total			Total
	Balance at December 31, 2014	$	221		$	925		$	132		$	74		$	(531	)	$	600		$	821
	Additions	121			44			3			—			—			47			168
	Amortization:
	Periodic amortization	(126		)	(29		)	(7		)	(3		)	—			(39		)	(165		)
	Included in realized gains	—			2			—			—			—			2			2
	Foreign currency translation	1			—			—			—			—			—			1
	Change in unrealized	—			—			—			—			(71		)	(71		)	(71		)
	Balance at March 31, 2015	$	217		$	942		$	128		$	71		$	(602	)	$	539		$	756
	Balance at December 31, 2013	$	211		$	875		$	149		$	85		$	(345	)	$	764		$	975
	Additions	124			50			4			—			—			54			178
	Periodic amortization	(121		)	(27		)	(7		)	(3		)	—			(37		)	(158		)
	Change in unrealized	—			—			—			—			(105		)	(105		)	(105		)
	Balance at March 31, 2014	$	214		$	898		$	146		$	82		$	(450	)	$	676		$	890

Managed_Investment_Entities_Ta

Managed Investment Entities (Tables)	3 Months Ended
	Mar. 31, 2015
Variable Interest Entity, Primary Beneficiary, Does Not Hold Majority Voting Interest, Disclosures [Abstract]
Selected financial information related to collateralized loan obligations	Selected financial information related to the CLOs is shown below (in millions):
		Three months ended March 31,
		2015			2014
	Gains (losses) on change in fair value of assets/liabilities (a):
	Assets	$	33		$	(1	)
	Liabilities	(36		)	1
	Management fees paid to AFG	4			3
	CLO earnings attributable to AFG shareholders (b)	3			5
	(a)	Included in Revenues in AFG’s Statement of Earnings.
	(b)	Included in Earnings before income taxes in AFG’s Statement of Earnings.

LongTerm_Debt_Tables

Long-Term Debt (Tables)	3 Months Ended
	Mar. 31, 2015
Debt Disclosure [Abstract]
Schedule of long-term debt instruments	The carrying value of long-term debt consisted of the following (in millions):
		March 31,		December 31,
		2015		2014
	Direct Senior Obligations of AFG:
	9-7/8% Senior Notes due June 2019	$	350	$	350
	6-3/8% Senior Notes due June 2042	230		230
	5-3/4% Senior Notes due August 2042	125		125
	7% Senior Notes due September 2050	132		132
	Other	3		3
		840		840
	Direct Subordinated Obligations of AFG:
	6-1/4% Subordinated Debentures due September 2054	150		150
	Subsidiaries:
	Notes payable secured by real estate due 2015 through 2016	59		59
	National Interstate bank credit facility	12		12
		71		71
		$	1,061	$	1,061
Summary of secured and unsecured long-term debt	As shown below (in millions), the majority of AFG’s long-term debt is unsecured obligations of the holding company and its subsidiaries:
		March 31,		December 31,
		2015		2014
	Senior unsecured obligations	$	852	$	852
	Subordinated unsecured obligations	150		150
	Obligations secured by real estate	59		59
		$	1,061	$	1,061

Shareholders_Equity_Tables

Shareholders' Equity (Tables)	3 Months Ended
	Mar. 31, 2015
Stockholders' Equity Note [Abstract]
Components of accumulated other comprehensive income (loss)	The progression of the components of accumulated other comprehensive income follows (in millions):
					Other Comprehensive Income
		AOCI			Pretax			Tax			Net			Attributable to			Attributable to			AOCI
		Beginning									of			noncontrolling			shareholders			Ending
		Balance									tax			interests						Balance
	Three months ended March 31, 2015
	Net unrealized gains on securities:
	Unrealized holding gains (losses) on securities arising during the period				$	106		$	(37	)	$	69		$	(1	)	$	68
	Reclassification adjustment for realized (gains) losses included in net earnings (a)				(19		)	7			(12		)	—			(12		)
	Total net unrealized gains on securities (b)	$	743		87			(30		)	57			(1		)	56			$	799
	Net unrealized gains on cash flow hedges	—			1			—			1			—			1			1
	Foreign currency translation adjustments	(8		)	(8		)	—			(8		)	—			(8		)	(16		)
	Pension and other postretirement plans adjustments	(8		)	—			—			—			—			—			(8		)
	Total	$	727		$	80		$	(30	)	$	50		$	(1	)	$	49		$	776
	Three months ended March 31, 2014
	Net unrealized gains on securities:
	Unrealized holding gains (losses) on securities arising during the period				$	211		$	(74	)	$	137		$	(3	)	$	134
	Reclassification adjustment for realized (gains) losses included in net earnings (a)				(18		)	6			(12		)	—			(12		)
	Total net unrealized gains on securities	$	563		193			(68		)	125			(3		)	122			$	685
	Foreign currency translation adjustments	1			(5		)	—			(5		)	—			(5		)	(4		)
	Pension and other postretirement plans adjustments	(4		)	—			—			—			—			—			(4		)
	Total	$	560		$	188		$	(68	)	$	120		$	(3	)	$	117		$	677
	(a)	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
	(b)	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.
Assumptions used in estimating weighted average fair value of options on grant date
		Three months ended March 31,
		2015			2014
	Exercise price	$	63.15		$	56.44
	Expected dividend yield	1.6		%	1.6		%
	Expected volatility	25		%	26		%
	Expected term (in years)	7.25			7.25
	Risk-free rate	1.88		%	2.2		%
	Grant date fair value	$	15.29		$	14.65

Income_Taxes_Tables

Income Taxes (Tables)	3 Months Ended
	Mar. 31, 2015
Income Tax Disclosure [Abstract]
Reconciliation of income taxes at the statutory rate and income taxes shown in the Statement of Earnings	The following is a reconciliation of income taxes at the statutory rate of 35% to the provision for income taxes as shown in the Statement of Earnings (dollars in millions):
		Three months ended March 31,
		2015					2014
		Amount			% of EBT		Amount			% of EBT
	Earnings before income taxes (“EBT”)	$	30				$	161
	Income taxes at statutory rate	$	10		35	%	$	56		35	%
	Effect of:
	Tax exempt interest	(7		)	(23	%)	(5		)	(3	%)
	Change in valuation allowance	(1		)	(3	%)	1			1	%
	Subsidiaries not in AFG’s tax return	1			3	%	1			1	%
	Other	2			5	%	1			—	%
	Provision for income taxes as shown in the Statement of Earnings	$	5		17	%	$	54		34	%

Accounting_Policies_Details

Accounting Policies (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Variable Interest Entity [Line Items]
Assets	$3,279		$3,108
Liabilities	2,952		2,819
Weighted average common shares adjustment related to stock-based compensation	1.8	2
Anti-dilutive potential common shares related to stock-based compensation plans	1.3	0.6
Maturities of short term investments	3 months
New collateralized loan obligation temporary warehousing entities [Member]
Variable Interest Entity [Line Items]
Assets	222
Liabilities	$177

Acquisitions_and_Sale_of_Busin2

Acquisitions and Sale of Businesses (Details) (Run-off long-term care insurance business [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Run-off long-term care insurance business [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Estimated sale proceeds	$14	[1]
Assets of businesses sold:
Cash and investments	1,397
Recoverables from reinsurers	603
Deferred policy acquisition costs	15
Other receivables	14
Other assets	7
Goodwill	2
Total assets	2,038
Liabilities of businesses sold:
Annuity benefits accumulated	270
Life, accident and health reserves	1,537
Other liabilities	27
Total liabilities	1,834
Reclassify net unrealized gain on marketable securities	28
Net assets of businesses sold	176
Pretax loss on subsidiaries	($162)
[1]	Includes fair value of the potential additional consideration and is shown net of estimated expenses.

Acquisitions_and_Sale_of_Busin3

Acquisitions and Sale of Businesses (Details 1) (Run-off long-term care insurance business [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Run-off long-term care insurance business [Member]
Life, accident and health net earned premiums:
Long-term care	$17	$19
Life operations	3	3
Net investment income	18	21
Realized gains (losses) on securities and other income	-2	1
Total revenues	36	44
Annuity benefits	2	2
Life, accident and health benefits:
Long-term care	21	29
Life operations	3	3
Annuity and supplemental insurance acquisition expenses	3	3
Other expenses	4	4
Total costs and expenses	33	41
Earnings before income taxes	$3	$3

Acquisitions_and_Sale_of_Busin4

Acquisitions and Sale of Businesses (Details Textual) (USD $)	3 Months Ended		0 Months Ended	9 Months Ended	12 Months Ended	0 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Apr. 01, 2014	Dec. 31, 2014	Dec. 31, 2014	Mar. 27, 2014
Acquisitions and Sale of Businesses [Line Items]
Payments to acquire business	$0	$8
Run-off long-term care insurance business [Member]
Acquisitions and Sale of Businesses [Line Items]
Sale proceeds	7
Additional sale proceeds based on the release of certain statutory liabilities of the legal entities sold	13
Carrying value of the assets and liabilities of business sold as a percentage of total assets and liabilities	4.00%
Summit Holding Southeast, Inc [Member]
Acquisitions and Sale of Businesses [Line Items]
Payments to acquire business			259
Capital contributions to acquired business			140
Total capital investment in acquired business			399
Net written premiums of acquired business				410	539
Net earned premiums of acquired business	129
Underwriting profit of acquired business	5
Selective Insurance Company of America Self-Insured Pooled Group [Member]
Acquisitions and Sale of Businesses [Line Items]
Payments to acquire business						8
Net written premiums of acquired business					23
In-force gross written premiums of acquired book of business						38
Gross written premiums of acquired business					33
Minimum [Member] | Run-off long-term care insurance business [Member]
Acquisitions and Sale of Businesses [Line Items]
Expected after-tax cash proceeds from the sale of business	105
Maximum [Member] | Run-off long-term care insurance business [Member]
Acquisitions and Sale of Businesses [Line Items]
Expected after-tax cash proceeds from the sale of business	$115

Segments_of_Operations_Details

Segments of Operations (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Segment Reporting Information [Line Items]
Total premiums earned	$946	$754
Net investment income	388	361
Other income	47	21
Revenues before realized gains (losses)	1,437	1,192
Realized gains on securities	19	19
Realized loss on subsidiaries	-162	0
Total revenues	1,294	1,211
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Net investment income	79	67
Other income	6	2
Revenues before realized gains (losses)	1,031	823
Annuity [Member]
Segment Reporting Information [Line Items]
Net investment income	292	275
Other income	24	18
Revenues before realized gains (losses)	316	293
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	46	51
Other [Member]
Segment Reporting Information [Line Items]
Revenues before realized gains (losses)	44	25
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Total premiums earned	313	301
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Total premiums earned	490	313
Specialty financial [Member]
Segment Reporting Information [Line Items]
Total premiums earned	120	117
Specialty Other [Member]
Segment Reporting Information [Line Items]
Total premiums earned	$23	$23

Segments_of_Operations_Details1

Segments of Operations (Details 1) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	$173		$142
Realized gains on securities	19		19
Realized loss on subsidiaries	-162		0
Earnings before income taxes	30		161
Property and Casualty Insurance [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	60		58
Investment and other income, net	73		54
Earnings before realized gains (losses) and income taxes	133		112
Annuity [Member]
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	75		73
Run-off Long-term Care and Life [Member]
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	4		-2
Other [Member]
Segment Reporting Information [Line Items]
Earnings before realized gains (losses) and income taxes	-39	[1]	-41	[1]
Specialty Property and transportation [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	7		6
Specialty casualty [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	28		38
Specialty financial [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	22		10
Specialty Other [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	3		5
Other Lines [Member]
Segment Reporting Information [Line Items]
Property and casualty insurance underwriting	$0		($1)
[1]	Includes holding company expenses. Also includes earnings of managed investment entities attributable to noncontrolling interest of less than $1 million for the first three months of 2014. Following the adoption of new guidance in the first quarter of 2015, there are no longer earnings of managed investment entities that are attributable to noncontrolling interests. See Note A — “Accounting Policies — Managed Investment Entities.”

Segments_of_Operations_Details2

Segments of Operations (Details Textual) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
	segment
Segment Reporting Information [Line Items]
Number of segments	4
Maximum [Member] | Other [Member]
Segment Reporting Information [Line Items]
Earnings (losses) of managed investment entities attributable to noncontrolling interests (are less than in 2014)		$1

Fair_Value_Measurements_Detail

Fair Value Measurements (Details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
In Millions, unless otherwise specified
Assets:
Fixed maturities, Available for sale, Fair Value	$31,968		$30,734
Fixed maturities, Trading, Fair Value	273		266
Assets of managed investment entities (MIE)	3,279		3,108
Variable annuity assets (separate accounts)	667	[1]	662	[1]
Other investments — derivatives	318		322
Total assets accounted for at fair value	38,215		36,788
Liabilities:
Liabilities of managed investment entities	2,952		2,819
Total liabilities accounted for at fair value	4,208		3,992
Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,243		1,160
Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	13		13
U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	330		353
States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	7,106		6,747
Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	184		194
Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,325		4,442
Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,403		2,451
Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,224		3,887
All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	13,396		12,660
Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	31,968		30,734
Fixed maturities, Trading, Fair Value	273		266
Equity securities [Member]
Assets:
Equity securities, Fair Value	1,710		1,696
Level 1 [Member]
Assets:
Assets of managed investment entities (MIE)	120		174
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,682		1,692
Liabilities:
Liabilities of managed investment entities	108		118
Total liabilities accounted for at fair value	108		118
Level 1 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 1 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 1 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	123		164
Level 1 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 1 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	38		36
Level 1 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	161		200
Fixed maturities, Trading, Fair Value	13		12
Level 1 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	1,388		1,306
Level 2 [Member]
Assets:
Assets of managed investment entities (MIE)	3,130		2,903
Variable annuity assets (separate accounts)	667	[1]	662	[1]
Other investments — derivatives	318		322
Total assets accounted for at fair value	35,200		33,741
Liabilities:
Liabilities of managed investment entities	2,818		0
Total liabilities accounted for at fair value	2,831		13
Level 2 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 2 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	13		13
Level 2 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	192		174
Level 2 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	7,045		6,647
Level 2 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	184		194
Level 2 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,019		4,142
Level 2 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	2,359		2,407
Level 2 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	4,013		3,661
Level 2 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	12,775		12,078
Level 2 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	30,587		29,303
Fixed maturities, Trading, Fair Value	260		254
Level 2 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	238		297
Level 3 [Member]
Assets:
Assets of managed investment entities (MIE)	29		31
Variable annuity assets (separate accounts)	0	[1]	0	[1]
Other investments — derivatives	0		0
Total assets accounted for at fair value	1,333		1,355
Liabilities:
Liabilities of managed investment entities	26		2,701
Total liabilities accounted for at fair value	1,269		3,861
Level 3 [Member] | Annuity benefits accumulated [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	1,243		1,160
Level 3 [Member] | Other liabilities [Member]
Liabilities:
Derivatives included in annuity benefits accumulated and other liabilities	0		0
Level 3 [Member] | U.S. Government and government agencies [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	15		15
Level 3 [Member] | States, municipalities and political subdivisions [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	61		100
Level 3 [Member] | Foreign government [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	0		0
Level 3 [Member] | Residential Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	306		300
Level 3 [Member] | Commercial Mortgage Backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	44		44
Level 3 [Member] | Asset-backed Securities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	211		226
Level 3 [Member] | All other corporate [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	583		546
Level 3 [Member] | Fixed maturities [Member]
Assets:
Fixed maturities, Available for sale, Fair Value	1,220		1,231
Fixed maturities, Trading, Fair Value	0		0
Level 3 [Member] | Equity securities [Member]
Assets:
Equity securities, Fair Value	$84		$93
[1]	Variable annuity liabilities equal the fair value of variable annuity assets.

Fair_Value_Measurements_Detail1

Fair Value Measurements (Details 1) (Embedded derivatives [Member])	3 Months Ended
	Mar. 31, 2015
Unobservable inputs used by management in determining fair value of embedded derivatives
Risk margin for uncertainty in cash flows	0.52%
Minimum [Member]
Unobservable inputs used by management in determining fair value of embedded derivatives
Adjustment for insurance subsidiary's credit risk	0.40%
Surrenders	4.00%
Partial surrenders	2.00%
Annuitizations	1.00%
Deaths	1.50%
Budgeted option costs	2.00%
Maximum [Member]
Unobservable inputs used by management in determining fair value of embedded derivatives
Adjustment for insurance subsidiary's credit risk	1.75%
Surrenders	16.00%
Partial surrenders	10.00%
Annuitizations	1.50%
Deaths	3.00%
Budgeted option costs	3.25%

Fair_Value_Measurements_Detail2

Fair Value Measurements (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
US Treasury and Government [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	$15	$15
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	0
Financial assets, Ending Balance	15	15
States, municipalities and political subdivisions [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	100	61
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	-39	0
Financial assets, Ending Balance	61	61
Residential Mortgage Backed Securities [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	300	316
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	-1	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	3	4
Purchases and issuances	0	0
Sales and settlements	-7	-8
Transfer into Level 3	41	32
Transfer out of Level 3	-30	-73
Financial assets, Ending Balance	306	272
Commercial Mortgage Backed Securities [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	44	28
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	0
Financial assets, Ending Balance	44	28
Asset-backed Securities [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	226	75
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	0
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	1
Purchases and issuances	5	50
Sales and settlements	-41	-1
Transfer into Level 3	21	81
Transfer out of Level 3	0	0
Financial assets, Ending Balance	211	206
All other corporate [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	546	335
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	6	3
Purchases and issuances	44	1
Sales and settlements	-13	-16
Transfer into Level 3	0	0
Transfer out of Level 3	0	-2
Financial assets, Ending Balance	583	322
Equity securities [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	93	31
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	0	1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	-2	2
Purchases and issuances	10	30
Sales and settlements	0	-9
Transfer into Level 3	0	0
Transfer out of Level 3	-17	-14
Financial assets, Ending Balance	84	41
Assets of Managed Investment Entities [Member]
Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial assets, Beginning Balance	31	30
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	-2	-1
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0	0
Purchases and issuances	0	0
Sales and settlements	0	0
Transfer into Level 3	0	0
Transfer out of Level 3	0	0
Financial assets, Ending Balance	$29	$29

Fair_Value_Measurements_Detail3

Fair Value Measurements (Details 3) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Liabilities of Managed Investment Entities [Member]
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial liabilities, Beginning Balance	($2,701)		($2,411)
Impact of accounting change	2,701	[1]
Total realized/unrealized gains (losses) included in Net income	0		1	[2]
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0
Purchases and issuances	0		-45
Sales and settlements	0		133
Transfer into Level 3	0		0
Transfer out of Level 3	0		0
Financial liabilities, Ending Balance	0		-2,322
Embedded derivatives [Member]
Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Roll Forward]
Financial liabilities, Beginning Balance	-1,160		-804
Impact of accounting change	0
Total realized/unrealized gains (losses) included in Net income	-50		-54
Total realized/unrealized gains (losses) included in other comprehensive income (loss)	0		0
Purchases and issuances	-47		-55
Sales and settlements	14		9
Transfer into Level 3	0		0
Transfer out of Level 3	0		0
Financial liabilities, Ending Balance	($1,243)		($904)
[1]	The impact of implementing new guidance adopted in 2015, as discussed above and in Note A — “Accounting Policies — Managed Investment Entities.”
[2]	Total realized/unrealized gains (losses) included in net income includes gains of $4 million related to liabilities outstanding as of March 31, 2014. See Note H — “Managed Investment Entities.”

Fair_Value_Measurements_Detail4

Fair Value Measurements (Details 4) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Financial assets:
Cash and cash equivalents	$1,212		$1,343		$1,876	$1,639
Mortgage loans	1,091		1,117
Policy loans	226		228
Financial liabilities:
Long-term debt	1,061		1,061
Level 1 [Member]
Financial assets:
Cash and cash equivalents	1,212		1,343
Mortgage loans	0		0
Policy loans	0		0
Total financial assets not accounted for at fair value	1,212		1,343
Financial liabilities:
Annuity benefits accumulated	0	[1]	0	[1]
Long-term debt	0		0
Total financial liabilities not accounted for at fair value	0		0
Level 2 [Member]
Financial assets:
Cash and cash equivalents	0		0
Mortgage loans	0		0
Policy loans	0		0
Total financial assets not accounted for at fair value	0		0
Financial liabilities:
Annuity benefits accumulated	0	[1]	0	[1]
Long-term debt	1,123		1,106
Total financial liabilities not accounted for at fair value	1,123		1,106
Level 3 [Member]
Financial assets:
Cash and cash equivalents	0		0
Mortgage loans	1,100		1,124
Policy loans	226		228
Total financial assets not accounted for at fair value	1,326		1,352
Financial liabilities:
Annuity benefits accumulated	23,966	[1]	23,187	[1]
Long-term debt	74		74
Total financial liabilities not accounted for at fair value	24,040		23,261
Carrying Value [Member]
Financial assets:
Cash and cash equivalents	1,212		1,343
Mortgage loans	1,091		1,117
Policy loans	226		228
Total financial assets not accounted for at fair value	2,529		2,688
Financial liabilities:
Annuity benefits accumulated	24,209	[1]	23,561	[1]
Long-term debt	1,061		1,061
Total financial liabilities not accounted for at fair value	25,270		24,622
Fair Value [Member]
Financial assets:
Cash and cash equivalents	1,212		1,343
Mortgage loans	1,100		1,124
Policy loans	226		228
Total financial assets not accounted for at fair value	2,538		2,695
Financial liabilities:
Annuity benefits accumulated	23,966	[1]	23,187	[1]
Long-term debt	1,197		1,180
Total financial liabilities not accounted for at fair value	$25,163		$24,367
[1]	Excludes life contingent annuities in the payout phase.

Fair_Value_Measurements_Detail5

Fair Value Measurements (Details Textual) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
	professional
Fair Value Measurements (Textual) [Abstract]
AFG's internal investment professionals	20
Level 3 assets as a percentage of total assets measured at fair value	3.50%
Percentage of level 3 assets that were priced using non-binding broker quotes	75.00%
Level 3 assets that were priced using non-binding broker quotes	$990
Percentage of internally developed Level 3 asset fair values to Shareholders' equity	6.00%
Total realized/unrealized gains (losses) included in net income on liabilities still outstanding			4
Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Percentage of internally developed Level 3 asset fair values to total assets (are less than)	1.00%
Fixed-indexed annuties (embedded derivative), majority of future years [Member] | Minimum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	5.00%
Fixed-indexed annuties (embedded derivative), majority of future years [Member] | Maximum [Member]
Fair Value Measurements (Textual) [Abstract]
Unobservable input surrenders used in Level 3 fair value determination	11.00%
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	1,240
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%
Common stocks [Member]
Fair Value Measurements (Textual) [Abstract]
Number of stocks transferred from Level 2 to Level 1	1
Fair value of assets transferred from Level 2 to Level 1	53
Perpetual preferred stocks [Member]
Fair Value Measurements (Textual) [Abstract]
Number of stocks transferred from Level 2 to Level 1	2
Fair value of assets transferred from Level 2 to Level 1	5
Number of stocks transferred from Level 1 to Level 2			8
Fair value of assets transferred from Level 1 to Level 2			55
Run-off long-term care insurance business [Member]
Fair Value Measurements (Textual) [Abstract]
Estimated sale proceeds of the run-off long-term care insurance business	$14	[1]
[1]	Includes fair value of the potential additional consideration and is shown net of estimated expenses.

Investments_Details

Investments (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	$30,090	$29,074
Fixed maturities, Available for sale, Fair Value	31,968	30,734
Equity securities, Available for sale, Amortized Cost	1,306	1,283
Equity securities, Available for sale, Fair Value	1,530	1,501
U.S. Government and government agencies [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	323	347
Fixed maturities, Available for sale, Fair Value	330	353
Fixed maturities, Available for sale, Gross Unrealized, Gains	10	8
Fixed maturities, Available for sale, Gross Unrealized, Losses	-3	-2
States, municipalities and political subdivisions [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	6,713	6,393
Fixed maturities, Available for sale, Fair Value	7,106	6,747
Fixed maturities, Available for sale, Gross Unrealized, Gains	401	364
Fixed maturities, Available for sale, Gross Unrealized, Losses	-8	-10
Foreign government [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	172	184
Fixed maturities, Available for sale, Fair Value	184	194
Fixed maturities, Available for sale, Gross Unrealized, Gains	12	10
Fixed maturities, Available for sale, Gross Unrealized, Losses	0	0
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	3,934	4,046
Fixed maturities, Available for sale, Fair Value	4,325	4,442
Fixed maturities, Available for sale, Gross Unrealized, Gains	404	411
Fixed maturities, Available for sale, Gross Unrealized, Losses	-13	-15
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	2,247	2,294
Fixed maturities, Available for sale, Fair Value	2,403	2,451
Fixed maturities, Available for sale, Gross Unrealized, Gains	156	158
Fixed maturities, Available for sale, Gross Unrealized, Losses	0	-1
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	4,175	3,872
Fixed maturities, Available for sale, Fair Value	4,224	3,887
Fixed maturities, Available for sale, Gross Unrealized, Gains	57	37
Fixed maturities, Available for sale, Gross Unrealized, Losses	-8	-22
All other corporate [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	12,526	11,938
Fixed maturities, Available for sale, Fair Value	13,396	12,660
Fixed maturities, Available for sale, Gross Unrealized, Gains	892	751
Fixed maturities, Available for sale, Gross Unrealized, Losses	-22	-29
Fixed maturities [Member]
Schedule of Available-for-sale Securities [Line Items]
Fixed maturities, Available for sale, Amortized Cost	30,090	29,074
Fixed maturities, Available for sale, Fair Value	31,968	30,734
Fixed maturities, Available for sale, Gross Unrealized, Gains	1,932	1,739
Fixed maturities, Available for sale, Gross Unrealized, Losses	-54	-79
Common stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities, Available for sale, Amortized Cost	888	885
Equity securities, Available for sale, Fair Value	1,087	1,087
Equity securities, Available for sale, Gross Unrealized, Gains	232	227
Equity securities, Available for sale, Gross Unrealized, Losses	-33	-25
Perpetual preferred stocks [Member]
Schedule of Available-for-sale Securities [Line Items]
Equity securities, Available for sale, Amortized Cost	418	398
Equity securities, Available for sale, Fair Value	443	414
Equity securities, Available for sale, Gross Unrealized, Gains	28	21
Equity securities, Available for sale, Gross Unrealized, Losses	($3)	($5)

Investments_Details_1

Investments (Details 1) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
U.S. Government and government agencies [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	$0	$0
Fair Value - Less than twelve months	6	39
Fair Value as % of Cost - Less than twelve months	100.00%	100.00%
Unrealized Loss - Twelve months or more	-3	-2
Fair Value - Twelve months or more	15	15
Fair Value as % of Cost - Twelve months or more	83.00%	88.00%
States, municipalities and political subdivisions [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-5	-2
Fair Value - Less than twelve months	507	222
Fair Value as % of Cost - Less than twelve months	99.00%	99.00%
Unrealized Loss - Twelve months or more	-3	-8
Fair Value - Twelve months or more	57	408
Fair Value as % of Cost - Twelve months or more	95.00%	98.00%
Residential Mortgage Backed Securities [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-5	-4
Fair Value - Less than twelve months	332	298
Fair Value as % of Cost - Less than twelve months	99.00%	99.00%
Unrealized Loss - Twelve months or more	-8	-11
Fair Value - Twelve months or more	193	209
Fair Value as % of Cost - Twelve months or more	96.00%	95.00%
Commercial Mortgage Backed Securities [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	0	-1
Fair Value - Less than twelve months	38	38
Fair Value as % of Cost - Less than twelve months	100.00%	97.00%
Unrealized Loss - Twelve months or more	0	0
Fair Value - Twelve months or more	10	11
Fair Value as % of Cost - Twelve months or more	100.00%	100.00%
Asset-backed Securities [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-3	-11
Fair Value - Less than twelve months	625	1,389
Fair Value as % of Cost - Less than twelve months	100.00%	99.00%
Unrealized Loss - Twelve months or more	-5	-11
Fair Value - Twelve months or more	461	622
Fair Value as % of Cost - Twelve months or more	99.00%	98.00%
All other corporate [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-18	-16
Fair Value - Less than twelve months	555	588
Fair Value as % of Cost - Less than twelve months	97.00%	97.00%
Unrealized Loss - Twelve months or more	-4	-13
Fair Value - Twelve months or more	75	433
Fair Value as % of Cost - Twelve months or more	95.00%	97.00%
Fixed maturities [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-31	-34
Fair Value - Less than twelve months	2,063	2,574
Fair Value as % of Cost - Less than twelve months	99.00%	99.00%
Unrealized Loss - Twelve months or more	-23	-45
Fair Value - Twelve months or more	811	1,698
Fair Value as % of Cost - Twelve months or more	97.00%	97.00%
Common stocks [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	-33	-25
Fair Value - Less than twelve months	218	260
Fair Value as % of Cost - Less than twelve months	87.00%	91.00%
Unrealized Loss - Twelve months or more	0	0
Fair Value - Twelve months or more	0	0
Fair Value as % of Cost - Twelve months or more	0.00%	0.00%
Perpetual preferred stocks [Member]
Available for sale securities in a continuous unrealized loss position
Unrealized Loss - Less than twelve months	0	-1
Fair Value - Less than twelve months	20	45
Fair Value as % of Cost - Less than twelve months	100.00%	98.00%
Unrealized Loss - Twelve months or more	-3	-4
Fair Value - Twelve months or more	$49	$55
Fair Value as % of Cost - Twelve months or more	94.00%	93.00%

Investments_Details_2

Investments (Details 2) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Other than Temporary Impairment, Credit Losses Recognized in Earnings [Roll Forward]
Balance at January 1	$170	$194
Additional credit impairments on:
Previously impaired securities	1	0
Securities without prior impairments	0	0
Reductions due to sales or redemptions	-3	-17
Balance at March 31	$168	$177

Investments_Details_3

Investments (Details 3) (Fixed Maturity [Member], USD $)	Mar. 31, 2015
In Millions, unless otherwise specified
Fixed Maturity [Member]
Amortized Cost Basis, Fiscal Year Maturity [Abstract]
One year or less	$958
After one year through five years	4,894
After five years through ten years	9,286
After ten years	4,596
Fixed maturities amortized cost, Subtotal	19,734
ABS (average life of approximately 4-1/2 years)	4,175
MBS (average life of approximately 4-1/2 years)	6,181
Amortized Cost	30,090
Fair Value, Fiscal Year Maturity [Abstract]
One year or less	978
After one year through five years	5,262
After five years through ten years	9,817
After ten years	4,959
Fixed maturities fair value, Subtotal	21,016
ABS (average life of approximately 4-1/2 years)	4,224
MBS (average life of approximately 4-1/2 years)	6,728
Fair Value	$31,968
Fair Value Percent, Fiscal Year Maturity [Abstract]
One year or less	3.00%
After one year through five years	16.00%
After five years through ten years	31.00%
After ten years	16.00%
Fixed maturities fair value, Subtotal, Percent	66.00%
ABS (average life of approximately 4-1/2 years)	13.00%
MBS (average life of approximately 4-1/2 years)	21.00%
Fair value, Total, Percent	100.00%

Investments_Details_4

Investments (Details 4) (USD $)	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014	Dec. 31, 2013
In Millions, unless otherwise specified
Unrealized gain on:
Pretax	$1,249		$1,162
Deferred Tax and Amounts Attributable to Noncontrolling Interests	-450		-419
Net	799	[1]	743	[1]	685	563
Fixed maturities - annuity segment [Member]
Unrealized gain on:
Pretax	1,349	[2]	1,157	[2]
Deferred Tax and Amounts Attributable to Noncontrolling Interests	-472	[2]	-405	[2]
Net	877	[2]	752	[2]
Fixed maturities - all other [Member]
Unrealized gain on:
Pretax	529		503
Deferred Tax and Amounts Attributable to Noncontrolling Interests	-196		-185
Net	333		318
Equity securities [Member]
Unrealized gain on:
Pretax	224		218
Deferred Tax and Amounts Attributable to Noncontrolling Interests	-81		-79
Net	143		139
Deferred policy acquisition costs - annuity segment [Member]
Unrealized gain on:
Pretax	-601		-531
Deferred Tax and Amounts Attributable to Noncontrolling Interests	210		186
Net	-391		-345
Annuity benefits accumulated [Member]
Unrealized gain on:
Pretax	-179		-112
Deferred Tax and Amounts Attributable to Noncontrolling Interests	63		39
Net	-116		-73
Life, accident and health reserves [Member]
Unrealized gain on:
Pretax	-109		-104
Deferred Tax and Amounts Attributable to Noncontrolling Interests	38		36
Net	-71		-68
Unearned revenue [Member]
Unrealized gain on:
Pretax	36		31
Deferred Tax and Amounts Attributable to Noncontrolling Interests	-12		-11
Net	$24		$20
[1]	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.
[2]	Unrealized gains on fixed maturity investments supporting AFG’s annuity benefits accumulated.

Investments_Details_5

Investments (Details 5) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Net Investment Income [Line Items]
Investment income	$393	$366
Investment expenses	-5	-5
Net investment income	388	361
Fixed maturities [Member]
Net Investment Income [Line Items]
Investment income	352	327
Equity securities [Member]
Net Investment Income [Line Items]
Investment income	17	16
Equity method investments [Member]
Net Investment Income [Line Items]
Investment income	3	6
Other [Member]
Net Investment Income [Line Items]
Investment income	$21	$17

Investments_Details_6

Investments (Details 6) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	$23	$20
Realized — impairments	-4	-1
Fixed maturities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	3	13
Realized — impairments	-5	-1
Change in unrealized	218	316
Equity securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	21	6
Realized — impairments	-2	0
Change in unrealized	6	13
Mortgage Loans and Other Investments [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	0	1
Realized — impairments	0	0
Change in unrealized	0	0
Other, Including DPAC and Reserves on Annuity and Long-term Care [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	-1	0
Realized — impairments	3	0
Change in unrealized	-137	-136
Total Pretax [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	23	20
Realized — impairments	-4	-1
Change in unrealized	87	193
Tax Effects [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	-8	-7
Realized — impairments	1	0
Change in unrealized	-30	-68
Noncontrolling Interests [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	0	0
Realized — impairments	0	0
Change in unrealized	-1	-3
Marketable Securities [Member]
Realized gains (losses) and changes in unrealized appreciation (depreciation) related to fixed maturity and equity security investments
Realized before impairments	15	13
Realized — impairments	-3	-1
Change in unrealized	$56	$122

Investments_Details_7

Investments (Details 7) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Fixed maturities [Member]
Gross realized gains and losses on the sale of available for sale fixed maturity and equity security investments
Gross gains	$5	$11
Gross losses	0	-1
Equity securities [Member]
Gross realized gains and losses on the sale of available for sale fixed maturity and equity security investments
Gross gains	21	8
Gross losses	$0	$0

Investments_Details_Textual

Investments (Details Textual) (USD $)	3 Months Ended		12 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	investment		investment
Investment [Line Items]
Percentage (based on amount of unrealized loss) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	55.00%
Percentage (based on fair value) of available for sale fixed maturities that are in an unrealized loss position and rated investment grade	79.00%
Other than temporary impairment charges	$4	$1
Average life of ABS	4 years 6 months
Average life of MBS	4 years 6 months
The number of investments in individual issuers that exceeded 10% of Shareholders’ Equity	0		0
Percentage increase in shareholders' equity	10.00%		10.00%
Residential Mortgage Backed Securities [Member]
Investment [Line Items]
Non-credit related portion of other-than-temporary impairment charges taken for securities still owned	218		220
Fixed maturities, Gross Unrealized, Losses	-13		-15
Securities with non-credit other-than-temporary impairment charges [Member]
Investment [Line Items]
Gross Unrealized, Gains	152		151
Gross Unrealized, Losses	-7		-8
Fixed maturities [Member]
Investment [Line Items]
Fixed maturities, Gross Unrealized, Losses	-54		-79
Number of available for sale securities in an unrealized loss position	480
Other than temporary impairment charges	5	1
Corporate bonds [Member]
Investment [Line Items]
Other than temporary impairment charges	5
Common stocks [Member]
Investment [Line Items]
Number of available for sale securities in an unrealized loss position	33
Other than temporary impairment charges	2
Equity securities, Gross Unrealized, Losses	-33		-25
Preferred stocks [Member]
Investment [Line Items]
Number of available for sale securities in an unrealized loss position	11
Equity securities, Gross Unrealized, Losses	-3		-5
Maximum [Member] | Residential Mortgage Backed Securities [Member]
Investment [Line Items]
Other than temporary impairment charges	$1
Number of available for sale securities in an unrealized loss position for twelve months or longer [Member] | Common stocks [Member]
Investment [Line Items]
Number of available for sale securities in an unrealized loss position	0
Number of available for sale securities in an unrealized loss position for twelve months or longer [Member] | Preferred stocks [Member]
Investment [Line Items]
Number of available for sale securities in an unrealized loss position	7

Derivatives_Details

Derivatives (Details) (Not Designated as Hedging Instrument [Member], USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Derivatives included in AFG' s Balance Sheet at fair value
Derivative asset, at fair value	$480	$499
Derivative liability, at fair value	1,256	1,173
MBS with embedded derivatives [Member] | Fixed maturities [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative asset, at fair value	164	158
Public company warrants [Member] | Equity securities [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative asset, at fair value	0	19
Interest rate swaptions [Member] | Other investments [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative asset, at fair value	0	0
Fixed-indexed annuities (embedded derivative) [Member] | Annuity benefits accumulated [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative liability, at fair value	1,243	1,160
Equity index call options [Member] | Other investments [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative asset, at fair value	316	322
Reinsurance contracts (embedded derivative) [Member] | Other liabilities [Member]
Derivatives included in AFG' s Balance Sheet at fair value
Derivative liability, at fair value	$13	$13

Derivatives_Details_1

Derivatives (Details 1) (Not Designated as Hedging Instrument [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	($32)	($26)
MBS with embedded derivatives [Member] | Realized gains on securities [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-2	3
Public company warrants [Member] | Realized gains on securities [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	-2
Interest rate swaptions [Member] | Realized gains on securities [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	0	-1
Fixed-indexed annuities (embedded derivative) [Member] | Annuity benefits [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	-50	-54
Equity index call options [Member] | Annuity benefits [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	20	30
Reinsurance contracts (embedded derivative) [Member] | Net investment income [Member]
Derivative, Gain (Loss) on Derivative, Net [Abstract]
Derivative Instruments Not Designated as Hedging Instruments, Gain (Loss), Net	$0	($2)

Derivatives_Details_Textual

Derivatives (Details Textual) (USD $)	3 Months Ended
	Mar. 31, 2015	Sep. 30, 2014	Dec. 31, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Indexed annuities as a percentage of annuity benefits	50.00%
Carrying value of collateral received to support purchased call options	$262,000,000
Not Designated as Hedging Instrument [Member] | Interest rate swaptions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Notional amount of derivative asset instrument outstanding	200,000,000
Payments to purchase swaptions	4,000,000
Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member] | Interest rate swaptions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Contract term of derivative instrument	5 years	5 years
Notional amount of derivative instrument outstanding	374,000,000	431,000,000	401,000,000
Net derivatives, at fair value (are less than in 2014)	-2,000,000
Gain (loss) reclassified from AOCI into net investment income	1,000,000
Gain (loss) on cash flow hedge ineffectiveness recorded in Net Earnings	0
Maximum [Member] | Cash Flow Hedges [Member] | Designated as Hedging Instrument [Member] | Interest rate swaptions [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Net derivatives, at fair value (are less than in 2014)			($1,000,000)

Deferred_Policy_Acquisition_Co2

Deferred Policy Acquisition Costs (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Deferred policy acquisition costs and present value of future profits, beginning balance	$821	$975
Deferred policy acquisition costs and present value of future profits, additions	168	178
Deferred policy acquisition costs and present value of future profits, periodic amortization	-165	-158
Deferred policy acquisition costs and present value of future profits, change included in realized gains	2
Deferred policy acquisition costs and present value of future profits, foreign currency translation	1
Deferred policy acquisition costs and present value of future profits, change in unrealized	-71	-105
Deferred policy acquisition costs and present value of future profits, ending balance	756	890
Property and Casualty Insurance [Member]
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	221	211
Deferred policy acquisition costs, additions	121	124
Deferred policy acquisition costs, periodic amortization	-126	-121
Deferred policy acquisition costs, foreign currency translation	1
Deferred policy acquisition costs, ending balance	217	214
Annuity and Run-off Long-term Care and Life [Member]
Movement Analysis of Deferred Policy Acquisition Costs [Roll Forward]
Deferred policy acquisition costs, beginning balance	925	875
Deferred policy acquisition costs, additions	44	50
Deferred policy acquisition costs, periodic amortization	-29	-27
Deferred policy acquisition costs, change included in realized gains	2
Deferred policy acquisition costs, ending balance	942	898
Movement in Deferred Sales Inducements [Roll Forward]
Deferred sales inducements, beginning balance	132	149
Deferred sales inducements, additions	3	4
Deferred sales inducements, periodic amortization	-7	-7
Deferred sales inducements, change included in realized gains	0
Deferred sales inducements, ending balance	128	146
Movement in Present Value of Future Insurance Profits [Roll Forward]
Present value of future profits, beginning balance	74	85
Present value of future profits, periodic amortization	-3	-3
Present value of future profits, ending balance	71	82
Movement in Unrealized Gains (Losses) Related to Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Unrealized investment gains (losses), beginning balance	-531	-345
Unrealized investment gains (losses), change in unrealized	-71	-105
Unrealized investment gains (losses), ending balance	-602	-450
Movement Analysis of Deferred Policy Acquisition Costs and Present Value of Future Profits [Roll Forward]
Deferred policy acquisition costs and present value of future profits, beginning balance	600	764
Deferred policy acquisition costs and present value of future profits, additions	47	54
Deferred policy acquisition costs and present value of future profits, periodic amortization	-39	-37
Deferred policy acquisition costs and present value of future profits, change included in realized gains	2
Deferred policy acquisition costs and present value of future profits, change in unrealized	-71	-105
Deferred policy acquisition costs and present value of future profits, ending balance	$539	$676

Deferred_Policy_Acquisition_Co3

Deferred Policy Acquisition Costs (Details Textual) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Deferred Policy Acquisition Costs Disclosures [Abstract]
Accumulated amortization of present value of future profits	$212	$209

Managed_Investment_Entities_De

Managed Investment Entities (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015		Mar. 31, 2014
Gains (losses) on change in fair value of assets/liabilities:
Assets	$33	[1]	($1)	[1]
Liabilities	-36	[1]	1	[1]
Management fees paid to AFG	4		3
CLO earnings attributable to AFG shareholders	$3	[2]	$5	[2]
[1]	Included in Revenues in AFG’s Statement of Earnings.
[2]	Included in Earnings before income taxes in AFG’s Statement of Earnings.

Managed_Investment_Entities_De1

Managed Investment Entities (Details Textual) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
	collateralizedloanobligation
Variable Interest Entity [Line Items]
Percentage of investment of most subordinate debt tranche, Minimum	15.00%
Percentage of investment of most subordinate debt tranche, Maximum	51.20%
Number of collateralized loan obligation entities	12
Proceeds received by subsidiaries related to redemptions of managed investment entities liabilities	$1	$29
Difference between aggregate unpaid principal balance and fair value of CLOs' fixed maturity investments	54		83
Difference between aggregate unpaid principal balance and carrying value of CLOs' debt	119		131
Carrying amount of CLO loans in default	5		2
Aggregate unpaid principal balance of CLO loans in default	10		6
Variable interest entity, primary beneficiary [Member]
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations	325		289
Subordinated debt obligations [Member] | Variable interest entity, primary beneficiary [Member]
Variable Interest Entity [Line Items]
Aggregate fair value of investment in collateralized loan obligations	127
Senior debt obligations [Member]
Variable Interest Entity [Line Items]
Face amount of managed investment entities liabilities purchased by subsidiaries after issuance date		3
Amount paid by subsidiaries to purchase managed investment entities liabilities after issuance date		$3

Goodwill_and_Other_Intangibles1

Goodwill and Other Intangibles (Details Textual) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Goodwill and Intangible Assets Disclosure [Abstract]
Changes in the goodwill balance during the period	$0
Goodwill	201		201
Amortizable intangible assets related to property and casualty insurance acquisitions	47		49
Accumulated amortization	12		91
Amortization of intangible assets	$2	$3

LongTerm_Debt_Details

Long-Term Debt (Details) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Summary of Carrying value of long-term debt
Long-term debt	$1,061	$1,061
AFG [Member]
Summary of Carrying value of long-term debt
Other long-term debt	3	3
Long-term debt	840	840
Subsidiaries [Member]
Summary of Carrying value of long-term debt
Long-term debt	71	71
Notes payable secured by real estate due 2015 through 2016	59	59
National Interstate bank credit facility	12	12
9-7/8% Senior Notes due June 2019 [Member] | AFG [Member]
Summary of Carrying value of long-term debt
Senior Notes	350	350
6-3/8% Senior Notes due June 2042 [Member] | AFG [Member]
Summary of Carrying value of long-term debt
Senior Notes	230	230
5-3/4% Senior Notes due August 2042 [Member] | AFG [Member]
Summary of Carrying value of long-term debt
Senior Notes	125	125
7% Senior Notes due September 2050 [Member] | AFG [Member]
Summary of Carrying value of long-term debt
Senior Notes	132	132
6-1/4% Subordinated Debentures due September 2054 [Member] | AFG [Member]
Summary of Carrying value of long-term debt
Subordinated Debentures	$150	$150

LongTerm_Debt_Details_1

Long-Term Debt (Details 1) (USD $)	Mar. 31, 2015	Dec. 31, 2014
In Millions, unless otherwise specified
Summary showing division of total long term debt
Obligations secured by real estate	$59	$59
Long-term debt	1,061	1,061
Senior unsecured obligations [Member]
Summary showing division of total long term debt
Unsecured obligations	852	852
Subordinated unsecured obligations [Member]
Summary showing division of total long term debt
Unsecured obligations	$150	$150

LongTerm_Debt_Details_Textual

Long-Term Debt (Details Textual) (USD $)	3 Months Ended	0 Months Ended
	Mar. 31, 2015	Mar. 31, 2015	Dec. 31, 2014
Long-term Debt, Fiscal Year Maturity [Abstract]
Scheduled principal payments on debt in 2015	$14,000,000	$14,000,000
Scheduled principal payments on debt in 2016	45,000,000	45,000,000
Scheduled principal payments on debt in 2017	12,000,000	12,000,000
Scheduled principal payments on debt in 2018	0	0
Scheduled principal payments on debt in 2019	350,000,000	350,000,000
Scheduled principal payments on debt in 2020	0	0
Scheduled principal payments on debt after 2020	640,000,000	640,000,000
AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Revolving credit line	500,000,000	500,000,000
Amount borrowed under AFG revolving credit facility	0	0	0
Interest rate description for revolving credit facility	1.00% to 1.875% (currently 1.375%) over LIBOR
National Interstate [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Revolving credit line	100,000,000	100,000,000
Interest rate on revolving debt facility		1.20%
Loans payable under National Interstate bank credit facility	12,000,000	12,000,000
Interest rate description for revolving credit facility	six-month LIBOR plus 0.875% (currently 1.20%)
9-7/8% Senior Notes due June 2019 [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Stated interest rate, percentage	9.88%	9.88%
9-7/8% Senior Notes due June 2019 [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Senior Notes	350,000,000	350,000,000	350,000,000
6-3/8% Senior Notes due June 2042 [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Stated interest rate, percentage	6.38%	6.38%
6-3/8% Senior Notes due June 2042 [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Senior Notes	230,000,000	230,000,000	230,000,000
5-3/4% Senior Notes due August 2042 [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Stated interest rate, percentage	5.75%	5.75%
5-3/4% Senior Notes due August 2042 [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Senior Notes	125,000,000	125,000,000	125,000,000
7% Senior Notes due September 2050 [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Stated interest rate, percentage	7.00%	7.00%
7% Senior Notes due September 2050 [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Senior Notes	132,000,000	132,000,000	132,000,000
6-1/4% Subordinated Debentures due September 2054 [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Stated interest rate, percentage	6.25%	6.25%
6-1/4% Subordinated Debentures due September 2054 [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Subordinated Debentures	$150,000,000	$150,000,000	$150,000,000
LIBOR [Member] | AFG [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.38%
LIBOR [Member] | AFG [Member] | Minimum [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.00%
LIBOR [Member] | AFG [Member] | Maximum [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		1.88%
LIBOR [Member] | National Interstate [Member] | Maximum [Member]
Long-term Debt, Fiscal Year Maturity [Abstract]
Interest rate on revolving debt facility		0.88%

Shareholders_Equity_Details

Shareholders' Equity (Details) (USD $)	Mar. 31, 2015
Voting Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, par value	$0
Preferred Stock, shares authorized	12,500,000
Nonvoting Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, par value	$0
Preferred Stock, shares authorized	12,500,000

Shareholders_Equity_Details_1

Shareholders' Equity (Details 1) (USD $)	3 Months Ended
In Millions, unless otherwise specified	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.

Shareholders_Equity_Details_2

Shareholders' Equity (Details 2) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Stock Options, Valuation Assumptions
Exercise price	$63.15	$56.44
Expected dividend yield	1.60%	1.60%
Expected volatility	25.00%	26.00%
Expected term (in years)	7 years 3 months	7 years 3 months
Risk-free rate	1.88%	2.20%
Grant date fair value	$15.29	$14.65

Shareholders_Equity_Details_Te

Shareholders' Equity (Details Textual) (USD $)	3 Months Ended
In Millions, except Share data, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Net of tax unrealized gains (losses) related to credit-only impaired securities	$57		$58
Common Stock options issued under stock incentive plan, average exercise price	$63.15	$56.44
Compensation expense related to stock incentive plans	$6	$7
Stock Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Restricted Common Stock, shares issued	171,130
Restricted Common Stock, fair value per share	$63.15
Common Stock options issued under stock incentive plan	716,818
Common Stock options issued under stock incentive plan, average exercise price	$63.15
Annual Equity Bonus Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Other benefit plans, shares	54,732
Common Stock issued, fair value per share	$62.55

Income_Taxes_Details

Income Taxes (Details) (USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015	Mar. 31, 2014
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Earnings before income taxes (“EBT”)	$30	$161
Income taxes at statutory rate	10	56
Effect of tax exempt interest	-7	-5
Effect of change in valuation allowance	-1	1
Effect of subsidiaries not in AFG's tax return	1	1
Effect of other income tax reconciliation	2	1
Provision for income taxes as shown on the Statement of Earnings	$5	$54
Effective Income Tax Rate Reconciliation, Percent [Abstract]
Income taxes at statutory rate as a percentage of EBT	35.00%	35.00%
Effect of tax exempt interest as a percentage of EBT	-23.00%	-3.00%
Effect of change in valuation allowance as a percentage of EBT	-3.00%	1.00%
Effect of subsidiaries not in AFG's tax return as a percentage of EBT	3.00%	1.00%
Effect of other income tax reconciliation as a percentage of EBT	5.00%	0.00%
Provision for income taxes as shown on the Statement of Earnings as a percentage of EBT	17.00%	34.00%

Income_Taxes_Details_Textual

Income Taxes (Details Textual)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Tax Disclosure [Abstract]
Statutory rate of income taxes	35.00%	35.00%
Effective tax rate excluding the tax benefit from the loss on the sale of business	32.00%

Contingencies_Contingencies_De

Contingencies Contingencies (Details) (Run-off long-term care insurance business [Member], USD $)	3 Months Ended
In Millions, unless otherwise specified	Mar. 31, 2015
Run-off long-term care insurance business [Member]
Loss Contingencies [Line Items]
Pretax loss on subsidiaries	($162)