Condensed Consolidating Financial Information - Statement of Cash Flows (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	$ 264.5	$ 270.6
Investing activities:
Purchase of equipment and improvements	(136.7)	(83.5)
Acquisitions, net	(65.4)	(86.4)
Other	(25.0)
Net cash used in continuing investing activities	(227.1)	(169.9)
Financing activities:
Net (repayments) borrowings of long-term debt	(99.1)	(194.2)
Net (repayments) borrowings of floor plan notes payable - non-trade	(163.0)	120.3
Issuance of 5.50% senior subordinated notes	500.0
Payment of debt issuance costs	(6.6)	(1.7)
Repurchases of common stock	(173.6)	(22.0)
Dividends	(46.4)	(40.7)
Other	(9.8)	0.2
Net cash provided by (used in) continuing financing activities	1.5	(138.1)
Net cash provided by discontinued operations	2.9	40.9
Effect of exchange rate changes on cash and cash equivalents	(6.7)	(0.4)
Net change in cash and cash equivalents	35.1	3.1
Cash and cash equivalents, beginning of period	62.4	36.3
Cash and cash equivalents, end of period	97.5	39.4
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	(90.1)	9.4
Investing activities:
Purchase of equipment and improvements	(0.4)	(0.7)
Net cash used in continuing investing activities	(0.4)	(0.7)
Financing activities:
Net (repayments) borrowings of long-term debt	(160.0)	(10.0)
Net (repayments) borrowings of floor plan notes payable - non-trade	(149.7)	64.0
Issuance of 5.50% senior subordinated notes	500.0
Payment of debt issuance costs	(6.6)
Repurchases of common stock	(173.6)	(22.0)
Dividends	(46.4)	(40.7)
Distributions from (to) parent	126.8
Net cash provided by (used in) continuing financing activities	90.5	(8.7)
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	109.5	73.8
Investing activities:
Purchase of equipment and improvements	(149.9)	(40.0)
Acquisitions, net	(65.1)	(21.7)
Other	0.4
Net cash used in continuing investing activities	(214.6)	(61.7)
Financing activities:
Net (repayments) borrowings of long-term debt	36.9	(5.1)
Net (repayments) borrowings of floor plan notes payable - non-trade	209.3	(54.7)
Other	(5.2)
Distributions from (to) parent	(125.0)	7.4
Net cash provided by (used in) continuing financing activities	116.0	(52.4)
Net cash provided by discontinued operations	0.3	40.3
Net change in cash and cash equivalents	11.2
Cash and cash equivalents, end of period	11.2
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	245.1	187.4
Investing activities:
Purchase of equipment and improvements	13.6	(42.8)
Acquisitions, net	(0.3)	(64.7)
Other	(25.4)
Net cash used in continuing investing activities	(12.1)	(107.5)
Financing activities:
Net (repayments) borrowings of long-term debt	24.0	(179.1)
Net (repayments) borrowings of floor plan notes payable - non-trade	(222.6)	111.0
Payment of debt issuance costs		(1.7)
Other	(4.6)	0.2
Distributions from (to) parent	(1.8)	(7.4)
Net cash provided by (used in) continuing financing activities	(205.0)	(77.0)
Net cash provided by discontinued operations	2.6	0.6
Effect of exchange rate changes on cash and cash equivalents	(6.7)	(0.4)
Net change in cash and cash equivalents	23.9	3.1
Cash and cash equivalents, beginning of period	62.4	36.3
Cash and cash equivalents, end of period	$ 86.3	$ 39.4