Related Party Transactions (Details 2)	3 Months Ended	12 Months Ended
	Sep. 30, 2015	Dec. 31, 2015
Audi, Mercedes-Benz, Sprinter, Porsche, Smart | Fairfield, Connecticut
Related party transactions
Ownership percentage of Consolidated Entity		81.03%
Audi, Mercedes-Benz, Sprinter, Porsche, Smart | Fairfield, Connecticut | Lucio A. Noto
Related party transactions
Ownership percentage in joint venture		18.97%
Percentage of operating profit		20.00%
Ownership percentage, option to purchase		20.00%
Mercedes-Benz | Greenwich, Connecticut
Related party transactions
Ownership percentage of Consolidated Entity		80.00%
Mercedes-Benz | Greenwich, Connecticut | Lucio A. Noto
Related party transactions
Ownership percentage in joint venture		20.00%
Lexus Toyota Volkswagen | Frankfurt, Germany
Related party transactions
Ownership percentage of Equity Method Investment		50.00%
Audi, Citroen, Kia, Maserati, SEAT, Skoda, Toyota, Volkswagen | Aachen, Germany
Related party transactions
Ownership percentage of Consolidated Entity		60.00%
Additional ownership percentage acquired	10.00%
BMW, MINI, Maserati | Northern Italy
Related party transactions
Ownership percentage of Consolidated Entity		70.00%
BMW/Mini | Barcelona Spain
Related party transactions
Ownership percentage of Equity Method Investment		50.00%
Penske Commercial Leasing Australia
Related party transactions
Ownership percentage of Equity Method Investment		45.00%
Penske Vehicle Services
Related party transactions
Ownership percentage of Equity Method Investment		31.00%
National Powersport Auctions
Related party transactions
Ownership percentage of Equity Method Investment		7.00%
PTG
Related party transactions
Ownership percentage of Consolidated Entity		96.00%
i.M. Branded
Related party transactions
Ownership percentage of Consolidated Entity		90.00%