Debt (Long-Term Debt) (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2022	Dec. 31, 2021
Debt Instruments [Abstract]
Less: current maturities	$ (12.6)	$ (12.2)
Long-term debt, net of current maturities	3,586.9	2,846.2
Recourse
Debt Instruments [Abstract]
Long-term debt	3,625.5	2,880.6
Less: unamortized debt discounts and debt issuance costs	(26.0)	(22.2)
Less: current maturities	(12.6)	(12.2)
Long-term debt, net of current maturities	$ 3,586.9	2,846.2
Senior Notes at Three Point Five Percent Due 2024 [Member] \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	3.50%
Debt instrument, maturity date	Nov. 15, 2024
Senior notes	$ 450.0	450.0
Senior Notes at Four Point Five Percent Due 2025 [Member] \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	4.50%
Debt instrument, maturity date	Oct. 01, 2025
Senior notes	$ 450.0	450.0
Senior Notes at Three Point Eight Percent Due 2027 [Member] \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	3.80%
Debt instrument, maturity date	Nov. 15, 2027
Senior notes	$ 300.0	300.0
Senior Notes at One Point Nine Five Percent Due 2028 \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	1.95%
Debt instrument, maturity date	Aug. 01, 2028
Senior notes	$ 400.0	400.0
Senior Notes at Four Point Seven Five Percent Due 2030 \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	4.75%
Debt instrument, maturity date	Jun. 01, 2030
Senior notes	$ 500.0	500.0
Senior Notes at Two Point Four Percent Due 2031 \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	2.40%
Debt instrument, maturity date	Aug. 01, 2031
Senior notes	$ 450.0	450.0
Senior Notes at Three Point Eight Five Percent Due 2032 \| Senior Notes [Member] \| Recourse
Debt Instruments [Abstract]
Percentage interest on debt instrument	3.85%
Debt instrument, maturity date	Mar. 01, 2032
Senior notes	$ 700.0	0.0
Revolving Credit Facility Due 2025 [Member] \| Recourse
Debt Instruments [Abstract]
Revolving credit facility, amount outstanding	$ 0.0	0.0
Revolving Credit Facility Due 2025 [Member] \| Line of Credit [Member]
Debt Instruments [Abstract]
Debt instrument, maturity date	Mar. 26, 2025
Revolving Credit Facility Due 2025 [Member] \| Line of Credit [Member] \| Recourse
Debt Instruments [Abstract]
Debt instrument, maturity date	Mar. 26, 2025
Other Debt [Member] \| Recourse
Debt Instruments [Abstract]
Other debt	$ 375.5	$ 330.6

Finance leases for real property and equipment classified as long-term debt.

No definition available.

Name:	an_FinanceLeasesIncludedInLongtermDebt
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- 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

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

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

+ References

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Balance Type:	na
Period Type:	instant

- Definition

Date when the debt instrument is scheduled to be fully repaid, in YYYY-MM-DD format.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unamortized debt discount (premium) and debt issuance costs.

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

- References

No definition available.

+ Details

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- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, classified as noncurrent.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, classified as current.

+ References

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of long-term debt and lease obligation, including portion classified as current.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
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