Condensed Consolidating Financial Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	$ 198.6	$ 82.6
Investing activities:
Purchase of equipment and improvements	(36.9)	(46.8)
Acquisitions, net	(314.2)	(0.4)
Other	9.0	(25.7)
Net cash used in continuing investing activities	(342.1)	(72.9)
Financing activities:
Net borrowings of long-term debt	153.1	111.5
Net borrowings (repayments) of floor plan notes payable—non-trade	63.0	54.9
Repurchases of common stock	(2.7)	(167.9)
Dividends	(25.6)	(23.3)
Other		(4.6)
Net cash provided by (used in) continuing financing activities	187.8	(29.4)
Net cash provided by discontinued operations	2.5	2.2
Effect of exchange rate changes on cash and cash equivalents	1.4	0.7
Net change in cash and cash equivalents	48.2	(16.8)
Cash and cash equivalents, beginning of period	24.0	62.4
Cash and cash equivalents, end of period	72.2	45.6
Penske Automotive Group
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	(17.1)	(12.5)
Investing activities:
Purchase of equipment and improvements	(0.4)	(0.4)
Net cash used in continuing investing activities	(0.4)	(0.4)
Financing activities:
Net borrowings of long-term debt	47.0	77.0
Net borrowings (repayments) of floor plan notes payable—non-trade	(1.2)	0.3
Repurchases of common stock	(2.7)	(167.9)
Dividends	(25.6)	(23.3)
Distributions from (to) parent		126.8
Net cash provided by (used in) continuing financing activities	17.5	12.9
Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	127.1	104.2
Investing activities:
Purchase of equipment and improvements	(20.1)	(26.4)
Acquisitions, net	(199.2)
Other	9.0	(0.3)
Net cash used in continuing investing activities	(210.3)	(26.7)
Financing activities:
Net borrowings of long-term debt	12.7	21.2
Net borrowings (repayments) of floor plan notes payable—non-trade	59.4	28.5
Distributions from (to) parent	0.7	(126.8)
Net cash provided by (used in) continuing financing activities	72.8	(77.1)
Net cash provided by discontinued operations	2.5	(0.4)
Net change in cash and cash equivalents	(7.9)
Cash and cash equivalents, beginning of period	9.4
Cash and cash equivalents, end of period	1.5
Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	88.6	(9.1)
Investing activities:
Purchase of equipment and improvements	(16.4)	(20.0)
Acquisitions, net	(115.0)	(0.4)
Other		(25.4)
Net cash used in continuing investing activities	(131.4)	(45.8)
Financing activities:
Net borrowings of long-term debt	93.4	13.3
Net borrowings (repayments) of floor plan notes payable—non-trade	4.8	26.1
Other		(4.6)
Distributions from (to) parent	(0.7)
Net cash provided by (used in) continuing financing activities	97.5	34.8
Net cash provided by discontinued operations		2.6
Effect of exchange rate changes on cash and cash equivalents	1.4	0.7
Net change in cash and cash equivalents	56.1	(16.8)
Cash and cash equivalents, beginning of period	14.6	62.4
Cash and cash equivalents, end of period	$ 70.7	$ 45.6