Related Party Transactions - Joint ventures (Details)	2 Months Ended
	Feb. 22, 2018	Dec. 31, 2017
Audi, Mercedes-Benz, Sprinter, Porsche | Fairfield, Connecticut
Related party transactions
Ownership percentage of Consolidated Entity		80.00%
Audi, Mercedes-Benz, Sprinter, Porsche | Fairfield, Connecticut | Lucio A. Noto
Related party transactions
Ownership percentage in joint venture		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%
BMW, MINI, Maserati, Porsche, Audi, Land Rover and Volvo | Northern Italy
Related party transactions
Ownership percentage of Consolidated Entity		84.00%
Audi, Maserati, SEAT, Skoda, Volkswagen | Aachen, Germany
Related party transactions
Ownership percentage of Consolidated Entity	75.40%	68.00%
Additional ownership percentage acquired	7.40%
Lexus Toyota Volkswagen | Frankfurt, Germany
Related party transactions
Ownership percentage of equity method investment		50.00%
BMW, MINI | Barcelona Spain
Related party transactions
Ownership percentage of equity method investment		50.00%
BMW, MINI, Rolls-Royce, Ferrari and ALPINA | Tokyo, Japan
Related party transactions
Ownership percentage of equity method investment		49.00%
Penske Commercial Leasing Australia
Related party transactions
Ownership percentage of equity method investment		28.00%
PTL
Related party transactions
Ownership percentage of equity method investment		28.90%