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

No definition available.

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- Definition

Represents the minimum number of vehicle brands offered.

+ References

No definition available.

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- Definition

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

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No definition available.

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Represents the minimum number of vehicles retailed and wholesaled.

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- Definition

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

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No definition available.

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- Definition

Number of franchises acquired.

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No definition available.

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- Definition

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

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No definition available.

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- Definition

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

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No definition available.

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- Definition

Represents the number of operating franchises.

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No definition available.

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Total number of owned and operated franchises.

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No definition available.

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Number of owned and operated franchises in domestic country.

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No definition available.

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- Definition

Number of owned and operated franchises in foreign countries.

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No definition available.

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- Definition

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

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No definition available.

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The number of retail locations operated.

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No definition available.

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- Definition

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

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No definition available.

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No definition available.

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- 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.

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- Definition

This element represents the aggregate cost of investments accounted for under the equity method of accounting.

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- Definition

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

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- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

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Interim Financial Statements - Business Overview (Details) $ in Millions			3 Months Ended		12 Months Ended
	Sep. 07, 2017 USD ($)	Jul. 26, 2016	Mar. 31, 2018 USD ($) item	Mar. 31, 2017 USD ($)	Dec. 31, 2017 USD ($)
Interim Financial Statements
Total revenues \| $			$ 5,746.9	$ 5,081.1
PTL
Interim Financial Statements
Ownership acquired (as a percent)	5.50%
Ownership interest in Penske Truck Leasing Co (as a percent)		23.40%	28.90%
Cost of acquisition \| $	$ 239.1
Retail Automotive Dealership
Interim Financial Statements
Total number of owned and operated franchises			342
Number of owned and operated franchises in US			151
Number of owned and operated franchises outside US			191
Minimum number of vehicles retailed and wholesaled			162,000
Minimum number of vehicle brands offered			40
Number of stand-alone used vehicle dealerships operated in the U.S. and U.K.			14
Number of acquired franchises			4
Number of franchises disposed			5
Commercial Vehicle Distribution
Interim Financial Statements
Minimum number of dealership locations			70
Number of retail dealerships owned by the reporting entity			8
Italy \| Retail Automotive Dealership
Interim Financial Statements
Number of acquired franchises			4
Automotive dealership revenues \| Geographic \| U.S. and Puerto Rico
Interim Financial Statements
Automotive dealership revenue (as a percent)			52.00%
Automotive dealership revenues \| Geographic \| Outside the U.S.
Interim Financial Statements
Automotive dealership revenue (as a percent)			48.00%
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			20
Number of full service retail locations operated			14
Number of collision centers operated			6
Retail Automotive Dealership
Interim Financial Statements
Total revenues \| $			$ 5,296.0	4,756.4	$ 19,800.0
Retail Commercial Truck Dealership
Interim Financial Statements
Total revenues \| $			292.4	211.7
Commercial Vehicle Distribution and Other
Interim Financial Statements
Total revenues \| $			$ 158.5	$ 113.0