Summary of Quarterly Financial Data (Unaudited) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Data
Total revenues	$ 4,887.8	$ 5,152.0	$ 5,254.1	$ 4,824.6	$ 4,921.3	$ 4,960.1	$ 4,920.6	$ 4,482.9	$ 20,118.5	$ 19,284.9	$ 17,232.0
Gross profit	727.3	744.2	771.3	723.8	717.1	729.2	731.3	689.9	2,966.6	2,867.5	2,579.2
Net income	82.7	88.5	95.0	80.2	71.3	87.5	95.7	75.9	346.4	330.4	290.1
Net income attributable to Penske Automotive Group common stockholders	$ 82.6	$ 87.5	$ 93.5	$ 79.3	$ 70.3	$ 86.6	$ 94.0	$ 75.2	$ 342.9	$ 326.1	$ 286.7
Diluted earnings per share attributable to Penske Automotive Group common stockholders (in dollars per share)	$ 0.97	$ 1.03	$ 1.10	$ 0.90	$ 0.78	$ 0.96	$ 1.04	$ 0.83	$ 3.99	$ 3.63	$ 3.17