The percentage of investment ownership.

No definition available.

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- Definition

Represents the ownership interest acquired by the entity during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	num:percentItemType
Balance Type:	na
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- Definition

Represents the minimum number of vehicle brands offered.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
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- Definition

Represents the minimum number of dealership locations wherein the vehicles were distributed and sold.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
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- Definition

Represents the minimum number of vehicles retailed and wholesaled.

+ References

No definition available.

+ Details

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Data Type:	xbrli:integerItemType
Balance Type:	na
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- Definition

Represents the number of franchises disposed of by the entity during the period.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
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- Definition

Represents the number of operating franchises.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Total number of owned and operated franchises.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of owned and operated franchises in domestic country.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number of owned and operated franchises in foreign countries.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of retail commercial vehicle dealerships owned by the reporting entity.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of retail locations operated.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of stand-alone used vehicle supercenters operated in the United States and United Kingdom.

+ References

No definition available.

+ Details

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Namespace Prefix:	pag_
Data Type:	xbrli:integerItemType
Balance Type:	na
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- References

No definition available.

+ Details

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 10
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+ Details

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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage investment held by members or limited partners of limited liability company (LLC) or limited partnership (LP).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 272
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6373374&loc=d3e70478-108055

+ Details

Name:	us-gaap_LimitedLiabilityCompanyLLCOrLimitedPartnershipLPMembersOrLimitedPartnersOwnershipInterest
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
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-Topic 606
-SubTopic 10
-Section 50
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=109196051&loc=SL49130545-203045

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

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Name:	srt_OwnershipAxis=pag_PenskeTruckLeasingCoLPMember
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Name:	srt_OwnershipAxis=pag_GermanAutomotiveDealershipJointVentureMember
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Name:	us-gaap_FranchisorDisclosureAxis=pag_RetailAutomotiveDealershipOperationsMember
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Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=pag_CommercialVehicleDistributionOperationsMember
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Name:	srt_StatementGeographicalAxis=country_DE
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Name:	us-gaap_ConcentrationRiskByTypeAxis=pag_PremiumBrandsConcentrationRiskMember
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Interim Financial Statements - Business Overview (Details) $ in Millions	3 Months Ended		12 Months Ended
	Mar. 31, 2019 USD ($) item	Mar. 31, 2018 USD ($)	Dec. 31, 2018 USD ($)
Interim Financial Statements
Total revenues \| $	$ 5,564.4	$ 5,746.9
Number of used vehicle supercenters operated in the U.S. and U.K.	14
PTL
Interim Financial Statements
Ownership interest in Penske Truck Leasing Co (as a percent)	28.90%
German Automotive Dealership Group
Interim Financial Statements
Ownership acquired (as a percent)	8.40%
Ownership interest (as a percent)	87.80%
Retail Automotive Dealership
Interim Financial Statements
Total number of owned and operated franchises	339
Number of owned and operated franchises in US	149
Number of owned and operated franchises outside US	190
Minimum number of vehicles retailed and wholesaled	157,000
Minimum number of vehicle brands offered	40
Number of franchises disposed	7
Commercial Vehicle Distribution
Interim Financial Statements
Minimum number of dealership locations	70
Number of retail dealerships owned by the reporting entity	10
U.S. \| Retail Automotive Dealership
Interim Financial Statements
Number of franchises disposed	6
Germany \| Retail Automotive Dealership
Interim Financial Statements
Number of franchises disposed	1
Automotive dealership revenues \| Geographic \| U.S. and Puerto Rico
Interim Financial Statements
Automotive dealership revenue (as a percent)	53.00%
Automotive dealership revenues \| Geographic \| Outside the U.S.
Interim Financial Statements
Automotive dealership revenue (as a percent)	47.00%
Automotive dealership revenues \| Premium brands
Interim Financial Statements
Automotive dealership revenue (as a percent)	70.00%
CarSense \| Retail Automotive Dealership
Interim Financial Statements
Number of retail locations operated	5
CarShop \| Retail Automotive Dealership
Interim Financial Statements
Number of retail locations operated	5
The Car People \| Retail Automotive Dealership
Interim Financial Statements
Number of retail locations operated	4
Penske Corporation \| PTL
Interim Financial Statements
Ownership interest in Penske Truck Leasing Co (as a percent)	41.10%
Mitsui and Co \| PTL
Interim Financial Statements
Ownership interest in Penske Truck Leasing Co (as a percent)	30.00%
PTG \| Retail Commercial Truck Dealership
Interim Financial Statements
Number of operating locations	19
Retail Automotive Dealership
Interim Financial Statements
Total revenues \| $	$ 5,091.2	5,296.0	$ 20,800.0
Retail Automotive Dealership \| U.S.
Interim Financial Statements
Total revenues \| $	2,722.8	2,750.9
Retail Commercial Truck Dealership
Interim Financial Statements
Total revenues \| $	332.3	292.4
Commercial Vehicle Distribution and Other
Interim Financial Statements
Total revenues \| $	$ 140.9	$ 158.5