Equity Method Investees (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Significant Equity Method Investees
Equity method investments	$ 1,688.1	$ 1,500.3
Equity in earnings of affiliates	374.5	169.0	$ 147.5
Condensed income statement information
Gross profit	4,440.8	3,184.5	3,455.5
Net income	1,192.7	545.3	435.1
Condensed balance sheet information
Current assets	4,075.4	4,408.8
Total assets	13,464.6	13,247.2
Current liabilities	4,274.6	4,674.9
Equity	4,095.0	3,326.1	2,811.6	$ 2,634.7
Total liabilities and equity	$ 13,464.6	13,247.2
The Nix Group
Significant Equity Method Investees
Ownership percentage of equity method investment	50.00%
Barcelona Premium SL
Significant Equity Method Investees
Ownership percentage of equity method investment	50.00%
Penske Commercial Leasing Australia
Significant Equity Method Investees
Ownership percentage of equity method investment	28.00%
PTL
Significant Equity Method Investees
Equity method investments	$ 1,643.1	1,419.2
PTL
Significant Equity Method Investees
Ownership interest in Penske Truck Leasing Co (as a percent)	28.90%
Equity method investees
Condensed income statement information
Revenues	$ 11,526.9	9,613.8	9,682.2
Gross profit	2,736.2	2,101.5	2,007.0
Net income	1,272.0	584.3	$ 509.8
Condensed balance sheet information
Current assets	1,564.7	1,456.4
Noncurrent assets	15,203.2	14,458.5
Total assets	16,767.9	15,914.9
Current liabilities	1,642.0	1,333.1
Noncurrent liabilities	10,785.6	10,952.6
Equity	4,340.3	3,629.2
Total liabilities and equity	$ 16,767.9	$ 15,914.9