Summary of Carrying value of long-term debt.

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- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Section 50
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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

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- Definition

Amount, after accumulated amortization, of debt issuance costs. Includes, but is not limited to, legal, accounting, underwriting, printing, and registration costs.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.17)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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- Definition

Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=120520924&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
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-Section S99
-Paragraph 1
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-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

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Long-Term Debt - Schedule of long-term debt (Details) - USD ($) $ in Millions	Jun. 30, 2020	May 29, 2020	Apr. 02, 2020	Dec. 31, 2019
Summary of Carrying value of long-term debt
Principal	$ 1,943			$ 1,493
Discount and Issue Costs	(31)			(20)
Carrying Value	1,912			1,473
Senior Notes \| AFG
Summary of Carrying value of long-term debt
Principal	1,318			1,018
Discount and Issue Costs	(12)			(5)
Carrying Value	$ 1,306			1,013
Senior Notes \| 4.50% Senior Notes due June 2047 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	4.50%
Summary of Carrying value of long-term debt
Principal	$ 590			590
Discount and Issue Costs	(2)			(2)
Carrying Value	$ 588			588
Senior Notes \| 3.50% Senior Notes due August 2026 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	3.50%
Summary of Carrying value of long-term debt
Principal	$ 425			425
Discount and Issue Costs	(3)			(3)
Carrying Value	$ 422			422
Senior Notes \| 5.25% Senior Notes due April 2030 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	5.25%		5.25%
Summary of Carrying value of long-term debt
Principal	$ 300		$ 300	0
Discount and Issue Costs	(7)			0
Carrying Value	293			0
Senior Notes \| Other \| AFG
Summary of Carrying value of long-term debt
Principal	3			3
Discount and Issue Costs	0			0
Carrying Value	3			3
Subordinated Debentures \| AFG
Summary of Carrying value of long-term debt
Principal	625			475
Discount and Issue Costs	(19)			(15)
Carrying Value	$ 606			460
Subordinated Debentures \| 5.125% Subordinate Debentures due December 2059 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	5.125%
Summary of Carrying value of long-term debt
Principal	$ 200			200
Discount and Issue Costs	(6)			(6)
Carrying Value	$ 194			194
Subordinated Debentures \| 6% Subordinated Debentures due November 2055 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	6.00%
Summary of Carrying value of long-term debt
Principal	$ 150			150
Discount and Issue Costs	(5)			(5)
Carrying Value	$ 145			145
Subordinated Debentures \| 5.625% Subordinated Debentures due June 2060 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	5.625%	5.625%
Summary of Carrying value of long-term debt
Principal	$ 150	$ 150		0
Discount and Issue Costs	(4)			0
Carrying Value	$ 146			0
Subordinated Debentures \| 5.875% Subordinated Debentures due March 2059 \| AFG
Debt Instrument [Line Items]
Interest rate on debt instruments	5.875%
Summary of Carrying value of long-term debt
Principal	$ 125			125
Discount and Issue Costs	(4)			(4)
Carrying Value	$ 121			$ 121