Condensed Consolidating Financial Information (Details 3) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Condensed consolidating statement of cash flows
Net cash provided by continuing operating activities	$ 270.1	$ 207.3
Investing activities:
Purchase of equipment and improvements	(82.9)	(81.5)
Acquisitions, net	(86.4)	(86.2)
Other		4.2
Net cash used in continuing investing activities	(169.3)	(163.5)
Financing activities:
Net repayments of long-term debt	(194.6)	(37.2)
Net borrowings (repayments) of floor plan notes payable - non-trade	122.3	32.4
Payment of deferred financing fees	(1.7)
Repurchases of common stock	(22.0)	(15.5)
Dividends	(40.7)	(33.5)
Other	0.2	0.3
Net cash used in continuing financing activities	(136.5)	(53.5)
Net cash provided by discontinued operations	36.5	20.8
Effect of exchange rates on cash and cash equivalents	(0.4)
Net change in cash and cash equivalents	0.4	11.1
Cash and cash equivalents, beginning of period	36.3	50.3
Cash and cash equivalents, end of period	36.7	61.4
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of cash flows
Net cash provided by continuing operating activities	9.4	33.5
Investing activities:
Purchase of equipment and improvements	(0.7)	(0.4)
Other		4.2
Net cash used in continuing investing activities	(0.7)	3.8
Financing activities:
Net repayments of long-term debt	(10.0)	10.0
Net borrowings (repayments) of floor plan notes payable - non-trade	64.0	1.7
Repurchases of common stock	(22.0)	(15.5)
Dividends	(40.7)	(33.5)
Net cash used in continuing financing activities	(8.7)	(37.3)
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by continuing operating activities	75.0	89.7
Investing activities:
Purchase of equipment and improvements	(40.0)	(60.5)
Acquisitions, net	(21.7)	(80.5)
Net cash used in continuing investing activities	(61.7)	(141.0)
Financing activities:
Net repayments of long-term debt	(5.7)	11.0
Net borrowings (repayments) of floor plan notes payable - non-trade	(54.7)	14.6
Distributions from (to) parent	7.4	3.6
Net cash used in continuing financing activities	(53.0)	29.2
Net cash provided by discontinued operations	39.7	9.0
Net change in cash and cash equivalents		(13.1)
Cash and cash equivalents, beginning of period		13.1
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by continuing operating activities	185.7	84.1
Investing activities:
Purchase of equipment and improvements	(42.2)	(20.6)
Acquisitions, net	(64.7)	(5.7)
Net cash used in continuing investing activities	(106.9)	(26.3)
Financing activities:
Net repayments of long-term debt	(178.9)	(58.2)
Net borrowings (repayments) of floor plan notes payable - non-trade	113.0	16.1
Payment of deferred financing fees	(1.7)
Other	0.2	0.3
Distributions from (to) parent	(7.4)	(3.6)
Net cash used in continuing financing activities	(74.8)	(45.4)
Net cash provided by discontinued operations	(3.2)	11.8
Effect of exchange rates on cash and cash equivalents	(0.4)
Net change in cash and cash equivalents	0.4	24.2
Cash and cash equivalents, beginning of period	36.3	37.2
Cash and cash equivalents, end of period	$ 36.7	$ 61.4