Condensed Consolidating Financial Information (Details 3) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	$ 193.6	$ 132.5
Investing activities:
Purchase of equipment and improvements	(33.6)	(39.8)
Acquisitions, net	(86.4)	(81.8)
Net cash used in continuing investing activities	(120.0)	(121.6)
Financing activities:
Net (repayments) borrowings of long-term debt	(139.3)	(26.3)
Net borrowings (repayments) of floor plan notes payable - non-trade	101.0	6.8
Payment of deferred financing fees	(1.2)
Repurchases of common stock	(14.0)
Dividends	(19.9)	(16.2)
Net cash used in continuing financing activities	(73.4)	(35.7)
Net cash provided by discontinued operations	33.4	29.6
Effect of exchange rate changes on cash and cash equivalents	(3.1)
Net change in cash and cash equivalents	30.5	4.8
Cash and cash equivalents, beginning of period	36.3	50.3
Cash and cash equivalents, end of period	66.8	55.1
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	(10.6)	9.7
Investing activities:
Purchase of equipment and improvements	(0.5)	(0.3)
Net cash used in continuing investing activities	(0.5)	(0.3)
Financing activities:
Net (repayments) borrowings of long-term debt		10.0
Net borrowings (repayments) of floor plan notes payable - non-trade	45.0	(3.2)
Repurchases of common stock	(14.0)
Dividends	(19.9)	(16.2)
Net cash used in continuing financing activities	11.1	(9.4)
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	17.1	109.8
Investing activities:
Purchase of equipment and improvements	(19.2)	(28.0)
Acquisitions, net	(21.7)	(80.0)
Net cash used in continuing investing activities	(40.9)	(108.0)
Financing activities:
Net (repayments) borrowings of long-term debt	(1.3)	(5.3)
Net borrowings (repayments) of floor plan notes payable - non-trade	(9.1)	(29.4)
Distributions from (to) parent	1.2	0.5
Net cash used in continuing financing activities	(9.2)	(34.2)
Net cash provided by discontinued operations	33.0	27.2
Net change in cash and cash equivalents		(5.2)
Cash and cash equivalents, beginning of period		13.1
Cash and cash equivalents, end of period		7.9
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of cash flows
Net cash provided by (used in) continuing operating activities	187.1	13.0
Investing activities:
Purchase of equipment and improvements	(13.9)	(11.5)
Acquisitions, net	(64.7)	(1.8)
Net cash used in continuing investing activities	(78.6)	(13.3)
Financing activities:
Net (repayments) borrowings of long-term debt	(138.0)	(31.0)
Net borrowings (repayments) of floor plan notes payable - non-trade	65.1	39.4
Payment of deferred financing fees	(1.2)
Distributions from (to) parent	(1.2)	(0.5)
Net cash used in continuing financing activities	(75.3)	7.9
Net cash provided by discontinued operations	0.4	2.4
Effect of exchange rate changes on cash and cash equivalents	(3.1)
Net change in cash and cash equivalents	30.5	10.0
Cash and cash equivalents, beginning of period	36.3	37.2
Cash and cash equivalents, end of period	$ 66.8	$ 47.2