Condensed Consolidating Financial Information - Balance Sheet (Details) - USD ($) $ in Millions	Sep. 30, 2016	May 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Dec. 31, 2014	Nov. 30, 2014	Aug. 31, 2012
Condensed consolidating balance sheet
Cash and cash equivalents	$ 89.4		$ 62.4	$ 49.7	$ 36.3
Accounts receivable, net	853.9		782.3
Inventories	3,279.7		3,463.5
Other current assets	105.3		85.6
Assets held for sale	7.5		12.7
Total current assets	4,335.8		4,406.5
Property and equipment, net	1,587.8		1,520.1
Intangible assets	1,725.2		1,731.2
Equity method investments	891.3		336.4
Other long-term assets	19.3		19.2
Total assets	8,559.4		8,013.4
Floor plan notes payable	2,073.2		2,247.2
Floor plan notes payable - non-trade	1,145.1		1,132.4
Accounts payable	506.1		493.8
Accrued expenses	389.2		378.1
Current portion of long-term debt	44.1		28.0
Liabilities held for sale	5.1		6.2
Total current liabilities	4,162.8		4,285.7
Long-term debt	1,833.5		1,247.0
Deferred tax liabilities	525.6		433.4
Other long-term liabilities	248.8		212.4
Total liabilities	6,770.7		6,178.5
Total equity	1,788.7		1,834.9
Total liabilities and equity	$ 8,559.4		$ 8,013.4
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%
5.50% senior subordinated notes due 2026
Condensed consolidating balance sheet
Interest rate (as a percent)	5.50%	5.50%
Domestic Subsidiaries ownership guaranteeing obligations (as a percent)	100.00%
Eliminations
Condensed consolidating balance sheet
Accounts receivable, net	$ (441.8)		$ (430.4)
Total current assets	(441.8)		(430.4)
Other long-term assets	(2,209.2)		(2,253.4)
Total assets	(2,651.0)		(2,683.8)
Accrued expenses	(441.8)		(430.4)
Total current liabilities	(441.8)		(430.4)
Long-term debt	(177.5)		(256.4)
Total liabilities	(619.3)		(686.8)
Total equity	(2,031.7)		(1,997.0)
Total liabilities and equity	(2,651.0)		(2,683.8)
Reportable legal entities | Penske Automotive Group
Condensed consolidating balance sheet
Accounts receivable, net	441.8		430.4
Other current assets	4.5		3.9
Total current assets	446.3		434.3
Property and equipment, net	3.5		4.0
Equity method investments	828.2		298.2
Other long-term assets	2,215.1		2,259.9
Total assets	3,493.1		2,996.4
Floor plan notes payable - non-trade	158.9		154.7
Accounts payable	3.4		4.8
Accrued expenses			0.1
Total current liabilities	162.3		159.6
Long-term debt	1,542.1		1,001.9
Total liabilities	1,704.4		1,161.5
Total equity	1,788.7		1,834.9
Total liabilities and equity	3,493.1		2,996.4
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating balance sheet
Cash and cash equivalents	1.3
Accounts receivable, net	360.0		400.8
Inventories	1,736.6		1,650.5
Other current assets	32.7		28.3
Assets held for sale	7.5		8.5
Total current assets	2,138.1		2,088.1
Property and equipment, net	946.7		822.0
Intangible assets	1,079.7		878.9
Other long-term assets	4.3		7.2
Total assets	4,168.8		3,796.2
Floor plan notes payable	1,063.9		1,295.0
Floor plan notes payable - non-trade	568.0		339.8
Accounts payable	159.2		143.3
Accrued expenses	146.5		112.3
Current portion of long-term debt	5.9		5.7
Liabilities held for sale	5.1		4.4
Total current liabilities	1,948.6		1,900.5
Long-term debt	187.9		109.2
Deferred tax liabilities	512.7		413.4
Other long-term liabilities	62.7		68.9
Total liabilities	2,711.9		2,492.0
Total equity	1,456.9		1,304.2
Total liabilities and equity	4,168.8		3,796.2
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating balance sheet
Cash and cash equivalents	88.1		62.4	$ 49.7	$ 36.3
Accounts receivable, net	493.9		381.5
Inventories	1,543.1		1,813.0
Other current assets	68.1		53.4
Assets held for sale			4.2
Total current assets	2,193.2		2,314.5
Property and equipment, net	637.6		694.1
Intangible assets	645.5		852.3
Equity method investments	63.1		38.2
Other long-term assets	9.1		5.5
Total assets	3,548.5		3,904.6
Floor plan notes payable	1,009.3		952.2
Floor plan notes payable - non-trade	418.2		637.9
Accounts payable	343.5		345.7
Accrued expenses	684.5		696.1
Current portion of long-term debt	38.2		22.3
Liabilities held for sale			1.8
Total current liabilities	2,493.7		2,656.0
Long-term debt	281.0		392.3
Deferred tax liabilities	12.9		20.0
Other long-term liabilities	186.1		143.5
Total liabilities	2,973.7		3,211.8
Total equity	574.8		692.8
Total liabilities and equity	$ 3,548.5		$ 3,904.6