Interim Financial Statements - Business Overview (Details) vehicle in Thousands, $ in Millions	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($) dealership franchise state vehicle location	Sep. 30, 2021 USD ($)	Sep. 30, 2022 USD ($) brand franchise dealership truck state vehicle location	Sep. 30, 2021 USD ($) franchise	Dec. 31, 2021 USD ($)	Jun. 30, 2022 USD ($)	Jan. 01, 2022 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($)
Interim Financial Statements
Total revenues	$ 6,920.7	$ 6,497.3	$ 20,803.0	$ 19,258.6
Number of vehicles retailed and wholesaled | vehicle			410
Minimum number of vehicle brands offered | brand			35
After-tax cumulative effect adjustment to retained earnings after adoption of Topic 842	$ 4,088.0	3,866.4	$ 4,088.0	3,866.4	$ 4,095.0	$ 4,219.4		$ 3,762.7	$ 3,326.1
PTL
Interim Financial Statements
Penske transportation solutions, ownership percentage	28.90%		28.90%				28.90%
Retained Earnings
Interim Financial Statements
After-tax cumulative effect adjustment to retained earnings after adoption of Topic 842	$ 4,504.5	3,921.5	$ 4,504.5	3,921.5	4,196.6	$ 4,506.7		$ 3,602.5	$ 3,151.3
Cumulative Effect, Period of Adoption, Adjustment
Interim Financial Statements
After-tax cumulative effect adjustment to retained earnings after adoption of Topic 842					(121.6)
Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Interim Financial Statements
After-tax cumulative effect adjustment to retained earnings after adoption of Topic 842					(121.6)
PTL
Interim Financial Statements
Number of vehicles in fleet | vehicle	400		400
PTL | Cumulative Effect, Period of Adoption, Adjustment | Retained Earnings
Interim Financial Statements
After-tax cumulative effect adjustment to retained earnings after adoption of Topic 842							$ 121.6
Revenues | Geographic | U.S. and Puerto Rico
Interim Financial Statements
Automotive dealership revenue (as a percent)			57.00%
Revenues | Geographic | Outside the U.S.
Interim Financial Statements
Automotive dealership revenue (as a percent)			43.00%
Penske Corporation | PTL
Interim Financial Statements
Ownership interest in Penske Truck Leasing Co			41.10%
Mitsui and Co | PTL
Interim Financial Statements
Ownership interest in Penske Truck Leasing Co			30.00%
Retail automotive dealership
Interim Financial Statements
Total revenues	$ 5,757.8	5,634.9	$ 17,784.3	17,039.4	$ 22,500.0
Total number of owned and operated franchises | franchise	340		340
Retail automotive dealership | Outside the U.S.
Interim Financial Statements
Number of owned and operated franchises outside US | franchise	188		188
Retail automotive dealership | United States And United Kingdom
Interim Financial Statements
Number of stand-alone used vehicle dealerships operated in United States and United Kingdom | dealership	21		21
Number of acquired franchises | franchise			19
Retail automotive dealership | U.S.
Interim Financial Statements
Total revenues	$ 3,400.8	3,271.2	$ 10,188.3	$ 9,890.5
Number of owned and operated franchises in US | franchise	152		152
Number of retail locations operated | dealership			8
Number of acquired franchises | franchise			4	1
Number of franchises awarded to the reporting entity | franchise			2
Retail automotive dealership | U.K.
Interim Financial Statements
Total revenues	$ 2,002.0	2,055.2	$ 6,461.3	$ 6,099.2
Number of retail locations operated | dealership			13
Number of acquired franchises | franchise			15
Number of retail locations disposed | franchise			1
Retail automotive dealership | Revenues | Premium brands
Interim Financial Statements
Automotive dealership revenue (as a percent)			70.00%
Retail commercial truck dealership
Interim Financial Statements
Total revenues	$ 1,019.5	$ 717.3	$ 2,580.5	$ 1,777.3
Number of vehicles retailed and wholesaled | truck			15,211
Number of operating locations | location	39		39
Retail commercial truck dealership | TEAM Truck Centres
Interim Financial Statements
Number of full service dealerships acquired | dealership			4
Retail commercial truck dealership | United States And Ontario, Canada
Interim Financial Statements
Number of dealerships | state	9		9