Condensed Consolidating Financial Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	$ 365.5	$ 391.5	$ 359.3
Investing activities:
Purchase of equipment and improvements	(203.1)	(199.5)	(176.1)
Acquisition of additional ownership interest in Penske Truck Leasing	(498.5)
Acquisitions, net	(140.8)	(156.9)	(355.0)
Other	5.7	4.7	(22.6)
Net cash used in continuing investing activities	(836.7)	(351.7)	(553.7)
Financing activities:
Net borrowings (repayments) of long-term debt	122.9	(62.1)	(71.3)
Net borrowings (repayments) of floor plan notes payable—non-trade	101.0	154.2	26.1
Payment of debt issuance costs	(6.7)	(1.8)	(4.4)
Repurchases of common stock	(173.6)	(48.9)	(15.5)
Dividends	(95.1)	(84.8)	(70.5)
Other	(9.7)	(5.9)	0.3
Net cash provided by (used in) continuing financing activities	438.8	(49.3)	164.7
Net cash provided by discontinued operations	3.1	37.0	17.0
Effect of exchange rate changes on cash and cash equivalents	(9.1)	(1.4)	(1.3)
Net change in cash and cash equivalents	(38.4)	26.1	(14.0)
Cash and cash equivalents, beginning of period	62.4	36.3	50.3
Cash and cash equivalents, end of period	24.0	62.4	36.3
5.50% senior subordinated notes due 2026
Financing activities:
Issuance of senior subordinated notes	500.0
5.375% Senior Subordinated Notes Due 2024
Financing activities:
Issuance of senior subordinated notes			300.0
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	(37.4)	(4.9)	(70.7)
Investing activities:
Purchase of equipment and improvements	(1.0)	(1.3)	(1.7)
Acquisition of additional ownership interest in Penske Truck Leasing	(498.5)
Other			4.2
Net cash used in continuing investing activities	(499.5)	(1.3)	2.5
Financing activities:
Net borrowings (repayments) of long-term debt	80.0	72.0	(100.0)
Net borrowings (repayments) of floor plan notes payable—non-trade	1.3	67.9	(41.4)
Payment of debt issuance costs	(6.7)		(4.4)
Repurchases of common stock	(173.6)	(48.9)	(15.5)
Dividends	(95.1)	(84.8)	(70.5)
Distributions from (to) parent	231.0
Net cash provided by (used in) continuing financing activities	536.9	6.2	68.2
Reportable legal entities | Penske Automotive Group | 5.50% senior subordinated notes due 2026
Financing activities:
Issuance of senior subordinated notes	500.0
Reportable legal entities | Penske Automotive Group | 5.375% Senior Subordinated Notes Due 2024
Financing activities:
Issuance of senior subordinated notes			300.0
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	52.1	230.3	209.7
Investing activities:
Purchase of equipment and improvements	(126.6)	(119.7)	(101.2)
Acquisitions, net		(93.2)	(175.3)
Other	17.0
Net cash used in continuing investing activities	(109.6)	(212.9)	(276.5)
Financing activities:
Net borrowings (repayments) of long-term debt	21.6	(4.9)	9.0
Net borrowings (repayments) of floor plan notes payable—non-trade	270.8	(58.3)	35.9
Distributions from (to) parent	(226.2)	8.8	5.5
Net cash provided by (used in) continuing financing activities	66.2	(54.4)	50.4
Net cash provided by discontinued operations	0.7	37.0	3.3
Net change in cash and cash equivalents	9.4		(13.1)
Cash and cash equivalents, beginning of period			13.1
Cash and cash equivalents, end of period	9.4
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	350.8	166.1	220.3
Investing activities:
Purchase of equipment and improvements	(75.5)	(78.5)	(73.2)
Acquisitions, net	(140.8)	(63.7)	(179.7)
Other	(11.3)	4.7	(26.8)
Net cash used in continuing investing activities	(227.6)	(137.5)	(279.7)
Financing activities:
Net borrowings (repayments) of long-term debt	21.3	(129.2)	19.7
Net borrowings (repayments) of floor plan notes payable—non-trade	(171.1)	144.6	31.6
Payment of debt issuance costs		(1.8)
Other	(9.7)	(5.9)	0.3
Distributions from (to) parent	(4.8)	(8.8)	(5.5)
Net cash provided by (used in) continuing financing activities	(164.3)	(1.1)	46.1
Net cash provided by discontinued operations	2.4		13.7
Effect of exchange rate changes on cash and cash equivalents	(9.1)	(1.4)	(1.3)
Net change in cash and cash equivalents	(47.8)	26.1	(0.9)
Cash and cash equivalents, beginning of period	62.4	36.3	37.2
Cash and cash equivalents, end of period	$ 14.6	$ 62.4	$ 36.3