Condensed Consolidating Financial Information (Details) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015	Dec. 31, 2014	Mar. 31, 2014	Dec. 31, 2013	Aug. 31, 2012	Nov. 30, 2014
Condensed consolidating balance sheet
Cash and cash equivalents	$ 66.8	$ 36.3	$ 55.1	$ 50.3
Accounts receivable, net	746.4	701.4
Inventories	2,885.7	2,819.2
Other current assets	106.7	124.7
Assets held for sale	62.2	186.1
Total current assets	3,867.8	3,867.7
Property and equipment, net	1,326.6	1,328.8
Intangible assets	1,657.7	1,652.5
Equity method investments	350.9	352.8
Other long-term assets	24.6	26.4
Total assets	7,227.6	7,228.2
Floor plan notes payable	1,915.8	1,812.6
Floor plan notes payable - non-trade	1,021.5	920.5
Accounts payable	454.1	417.6
Accrued expenses	342.9	310.3
Current portion of long-term debt	34.5	36.6
Liabilities held for sale	43.3	132.7
Total current liabilities	3,812.1	3,630.3
Long-term debt	1,174.1	1,316.0
Deferred tax liabilities	385.0	409.9
Other long-term liabilities	185.0	190.8
Total liabilities	5,556.2	5,547.0
Total equity	1,671.4	1,681.2
Total liabilities and equity	7,227.6	7,228.2
5.75% senior subordinated notes due 2022
Condensed consolidating balance sheet
Interest rate (as a percent)	5.75%	5.75%			5.75%
Domestic Subsidiaries ownership guaranteeing obligations (as a percent)	100.00%
5.375% senior subordinated notes due 2024
Condensed consolidating balance sheet
Interest rate (as a percent)	5.375%	5.375%				5.375%
Domestic Subsidiaries ownership guaranteeing obligations (as a percent)	100.00%
Eliminations
Condensed consolidating balance sheet
Accounts receivable, net	(415.0)	(409.6)
Total current assets	(415.0)	(409.6)
Other long-term assets	(2,014.8)	(1,990.8)
Total assets	(2,429.8)	(2,400.4)
Accrued expenses	(415.0)	(409.6)
Total current liabilities	(415.0)	(409.6)
Long-term debt	(274.2)	(247.0)
Total liabilities	(689.2)	(656.6)
Total equity	(1,740.6)	(1,743.8)
Total liabilities and equity	(2,429.8)	(2,400.4)
Reportable legal entities | Penske Automotive Group
Condensed consolidating balance sheet
Accounts receivable, net	415.0	409.6
Other current assets	5.3	4.5
Total current assets	420.3	414.1
Property and equipment, net	4.5	4.3
Equity method investments	288.1	285.5
Other long-term assets	2,031.4	2,005.0
Total assets	2,744.3	2,708.9
Floor plan notes payable - non-trade	131.8	86.8
Accounts payable	2.2	2.9
Accrued expenses	0.9
Total current liabilities	134.9	89.7
Long-term debt	938.0	938.0
Total liabilities	1,072.9	1,027.7
Total equity	1,671.4	1,681.2
Total liabilities and equity	2,744.3	2,708.9
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating balance sheet
Cash and cash equivalents			7.9	13.1
Accounts receivable, net	364.2	392.6
Inventories	1,488.4	1,481.5
Other current assets	27.4	58.3
Assets held for sale	28.2	150.4
Total current assets	1,908.2	2,082.8
Property and equipment, net	761.7	754.6
Intangible assets	834.2	818.4
Other long-term assets	2.4	4.4
Total assets	3,506.5	3,660.2
Floor plan notes payable	1,089.8	1,102.0
Floor plan notes payable - non-trade	389.0	398.1
Accounts payable	149.1	208.3
Accrued expenses	162.9	123.3
Current portion of long-term debt	6.9	4.6
Liabilities held for sale	17.8	105.9
Total current liabilities	1,815.5	1,942.2
Long-term debt	112.6	116.1
Deferred tax liabilities	362.0	385.6
Other long-term liabilities	67.5	66.9
Total liabilities	2,357.6	2,510.8
Total equity	1,148.9	1,149.4
Total liabilities and equity	3,506.5	3,660.2
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating balance sheet
Cash and cash equivalents	66.8	36.3	47.2	37.2
Accounts receivable, net	382.2	308.8
Inventories	1,397.3	1,337.7
Other current assets	74.0	61.9
Assets held for sale	34.0	35.7
Total current assets	1,954.3	1,780.4
Property and equipment, net	560.4	569.9
Intangible assets	823.5	834.1
Equity method investments	62.8	67.3
Other long-term assets	5.6	7.8
Total assets	3,406.6	3,259.5
Floor plan notes payable	826.0	710.6
Floor plan notes payable - non-trade	500.7	435.6
Accounts payable	302.8	206.4
Accrued expenses	594.1	596.6
Current portion of long-term debt	27.6	32.0
Liabilities held for sale	25.5	26.8
Total current liabilities	2,276.7	2,008.0
Long-term debt	397.7	508.9
Deferred tax liabilities	23.0	24.3
Other long-term liabilities	117.5	123.9
Total liabilities	2,814.9	2,665.1
Total equity	591.7	594.4
Total liabilities and equity	$ 3,406.6	$ 3,259.5