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

No definition available.

Name:	pag_InvestmentOwnershipPercentageAcquired
Namespace Prefix:	pag_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum number of vehicle brands offered.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Represents the minimum number of vehicles retailed and wholesaled.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of collision centers operated by the equity method investee.

+ References

No definition available.

+ Details

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

- Definition

Number of franchises acquired.

+ References

No definition available.

+ Details

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

- Definition

Number of brands represented by franchises awarded to the reporting entity.

+ References

No definition available.

+ Details

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

- Definition

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

+ References

No definition available.

+ Details

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

- Definition

Represents the number of full service retail locations operated by the equity method investee.

+ References

No definition available.

+ Details

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

- Definition

Represents the number of operating franchises.

+ References

No definition available.

+ Details

Name:	pag_NumberOfOperatingFranchises
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

Name:	pag_NumberOfOwnedAndOperatedFranchises
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

Name:	pag_NumberOfOwnedAndOperatedFranchisesInDomesticCountry
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

Name:	pag_NumberOfOwnedAndOperatedFranchisesInForeignCountries
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

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

- Definition

Represents the number of retail locations acquired.

+ References

No definition available.

+ Details

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

- References

No definition available.

+ Details

Name:	pag_SummaryOfSignificantAccountingPoliciesLineItems
Namespace Prefix:	pag_
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://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 18
-URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6351-108592

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13531-108611

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 275
-SubTopic 10
-Section 50
-Paragraph 20
-URI http://asc.fasb.org/extlink&oid=64851502&loc=d3e6404-108592

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 825
-SubTopic 10
-Section 50
-Paragraph 21
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=73719730&loc=d3e13537-108611

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of units or percentage investment held by one or more members or limited partners of the LLC or LP.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-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
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the purchase of or advances to an equity method investments, which are investments in joint ventures and entities in which the entity has an equity ownership interest normally of 20 to 50 percent and exercises significant influence.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 13
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3213-108585

+ Details

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

- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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

- Details

Name:	us-gaap_ScheduleOfEquityMethodInvestmentEquityMethodInvesteeNameAxis=pag_PenskeTruckLeasingCoLPMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=pag_CarSenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=pag_CarShopMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=pag_RetailAutomotiveDealershipOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=pag_RetailCommercialTruckDealershipOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FranchisorDisclosureAxis=pag_CommercialVehicleDistributionOperationsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=stpr_NJ
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=stpr_AZ
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=pag_UnitedKingdomMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pag_TypeOfDealershipAxis=pag_BmwMiniMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=country_US
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	pag_TypeOfDealershipAxis=pag_SmartMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=country_DE
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_SalesRevenueNetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_GeographicConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=pag_USAndPRMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementGeographicalAxis=pag_OutsideUSMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=pag_PremiumBrandsConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=pag_PenskeCorporationMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	dei_LegalEntityAxis=pag_MitsuiAndCoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=pag_RetailAutomotiveDealershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=pag_RetailCommercialTruckDealershipMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_StatementBusinessSegmentsAxis=pag_CommercialVehicleDistributionAndOtherMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Interim Financial Statements - Business Overview (Details) $ in Millions					1 Months Ended		3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017 item	Sep. 07, 2017 USD ($)	Jul. 27, 2016 USD ($)	Jul. 26, 2016	Dec. 31, 2016 item	Apr. 30, 2016 item	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) item	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Interim Financial Statements
Total revenues \| $							$ 5,524.4	$ 5,152.0	$ 15,988.9	$ 15,230.7
Cost of acquisition \| $									$ 239.1	498.5
PTL
Interim Financial Statements
Ownership acquired (as a percent)		5.50%	14.40%
Ownership interest in Penske Truck Leasing Co (as a percent)	28.90%		23.40%	9.00%
Cost of acquisition \| $		$ 239.1	$ 498.5
CarSense
Interim Financial Statements
Number of retail locations acquired									5
CarShop
Interim Financial Statements
Number of retail locations acquired									5
Retail Automotive Dealership
Interim Financial Statements
Total number of owned and operated franchises	354						354		354
Number of owned and operated franchises in US	162						162		162
Number of owned and operated franchises outside US	192						192		192
Minimum number of vehicles retailed and wholesaled									471,700
Minimum number of vehicle brands offered									40
Number of acquired franchises									8
Number of franchises awarded to the reporting entity									3
Number of franchises disposed									12
Retail Automotive Dealership \| CarSense
Interim Financial Statements
Number of retail locations acquired									5
Retail Automotive Dealership \| CarShop
Interim Financial Statements
Number of retail locations acquired									5
Retail Commercial Truck Dealership
Interim Financial Statements
Number of operating locations									20
Number of full service retail locations operated									14
Number of collision centers operated									6
Number of retail locations acquired					2	4
Commercial Vehicle Distribution
Interim Financial Statements
Minimum number of dealership locations									70
Number of retail dealerships owned by the reporting entity									10
New Jersey \| Retail Automotive Dealership
Interim Financial Statements
Number of acquired franchises									2
Arizona \| Retail Automotive Dealership
Interim Financial Statements
Number of acquired franchises									2
UK \| Retail Automotive Dealership
Interim Financial Statements
Number of acquired franchises									2
UK \| Retail Automotive Dealership \| BMW, MINI
Interim Financial Statements
Number of franchises disposed									3
U.S. \| Retail Automotive Dealership \| Smart
Interim Financial Statements
Number of franchises disposed									5
Germany \| Retail Automotive Dealership
Interim Financial Statements
Number of acquired franchises									2
Automotive dealership revenues \| Geographic \| U.S. and Puerto Rico
Interim Financial Statements
Automotive dealership revenue (as a percent)									58.00%
Automotive dealership revenues \| Geographic \| Outside the U.S.
Interim Financial Statements
Automotive dealership revenue (as a percent)									42.00%
Automotive dealership revenues \| Premium brands
Interim Financial Statements
Automotive dealership revenue (as a percent)									70.00%
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 acquired (as a percent)		10.00%
Ownership interest in Penske Truck Leasing Co (as a percent)	30.00%
Retail Automotive Dealership
Interim Financial Statements
Total revenues \| $							$ 5,085.4	4,772.1	$ 14,882.5	14,121.8	$ 18,700.0
Retail Commercial Truck Dealership
Interim Financial Statements
Total revenues \| $							299.6	266.1	739.8	782.3
Commercial Vehicle Distribution and Other
Interim Financial Statements
Total revenues \| $							$ 139.4	$ 113.8	$ 366.6	$ 326.6