Condensed Consolidating Financial Information (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Condensed consolidating statement of income
Revenues	$ 4,406.7	$ 3,630.6	$ 8,454.7	$ 6,979.9	$ 14,700.0
Cost of sales	3,739.8	3,071.1	7,163.8	5,893.8
Gross profit	666.9	559.5	1,290.9	1,086.1
Selling, general and administrative expenses	513.2	432.7	1,001.0	839.8
Depreciation	17.5	14.7	34.0	29.0
Operating income	136.2	112.1	255.9	217.3
Floor plan interest expense	(11.6)	(10.7)	(22.7)	(20.8)
Other interest expense	(13.1)	(11.9)	(26.2)	(23.4)
Equity in earnings of affiliates	10.9	8.9	16.0	11.2
Income from continuing operations before income taxes	122.4	98.4	223.0	184.3
Income taxes	(41.1)	(34.9)	(75.2)	(63.2)
Income from continuing operations	81.3	63.5	147.8	121.1
(Loss) income from discontinued operations, net of tax	(7.4)	(1.0)	(6.0)	(0.6)
Net income	73.9	62.5	141.8	120.5
Other Comprehensive Income (Loss), Net of Taxes	18.8	3.0	25.0	(34.1)
Comprehensive Income	92.7	65.5	166.8	86.4
Less: Comprehensive income attributable to the non-controlling interests	0.9	0.4	1.1	1.3
Comprehensive income attributable to Penske Automotive Group common stockholders	91.8	65.1	165.7	85.1
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries	(128.0)	(103.9)	(239.6)	(201.8)
Income from continuing operations before income taxes	(128.0)	(103.9)	(239.6)	(201.8)
Income taxes	43.3	36.2	81.2	68.4
Income from continuing operations	(84.7)	(67.7)	(158.4)	(133.4)
(Loss) income from discontinued operations, net of tax	7.4	1.0	6.0	0.6
Net income	(77.3)	(66.7)	(152.4)	(132.8)
Other Comprehensive Income (Loss), Net of Taxes	(18.4)	(2.6)	(25.2)	34.2
Comprehensive Income	(95.7)	(69.3)	(177.6)	(98.6)
Less: Comprehensive income attributable to the non-controlling interests			0.2	(0.5)
Comprehensive income attributable to Penske Automotive Group common stockholders	(95.7)	(69.3)	(177.8)	(98.1)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses	5.9	4.6	11.7	9.8
Depreciation	0.3	0.4	0.6	0.8
Operating income	(6.2)	(5.0)	(12.3)	(10.6)
Floor plan interest expense	(2.4)	(2.5)	(4.8)	(4.8)
Other interest expense	(7.4)	(5.4)	(14.5)	(11.7)
Equity in earnings of affiliates	9.4	6.9	13.6	8.8
Equity in earnings of subsidiaries	128.0	103.9	239.6	201.8
Income from continuing operations before income taxes	121.4	97.9	221.6	183.5
Income taxes	(41.1)	(34.8)	(75.2)	(63.1)
Income from continuing operations	80.3	63.1	146.4	120.4
(Loss) income from discontinued operations, net of tax	(7.4)	(1.0)	(6.0)	(0.6)
Net income	72.9	62.1	140.4	119.8
Other Comprehensive Income (Loss), Net of Taxes	18.8	3.0	25.0	(34.1)
Comprehensive Income	91.7	65.1	165.4	85.7
Less: Comprehensive income attributable to the non-controlling interests			(0.2)	0.5
Comprehensive income attributable to Penske Automotive Group common stockholders	91.7	65.1	165.6	85.2
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,480.6	2,196.0	4,661.1	4,156.9
Cost of sales	2,080.4	1,836.9	3,905.7	3,473.0
Gross profit	400.2	359.1	755.4	683.9
Selling, general and administrative expenses	302.5	272.0	589.1	522.0
Depreciation	9.8	8.5	19.1	16.5
Operating income	87.9	78.6	147.2	145.4
Floor plan interest expense	(5.4)	(5.0)	(10.4)	(9.7)
Other interest expense	(1.1)	(1.1)	(2.3)	(2.2)
Income from continuing operations before income taxes	81.4	72.5	134.5	133.5
Income taxes	(27.9)	(27.4)	(51.8)	(51.2)
Income from continuing operations	53.5	45.1	82.7	82.3
(Loss) income from discontinued operations, net of tax	0.2		7.2	0.8
Net income	53.7	45.1	89.9	83.1
Other Comprehensive Income (Loss), Net of Taxes	1.5	1.1	(0.9)	2.1
Comprehensive Income	55.2	46.2	89.0	85.2
Comprehensive income attributable to Penske Automotive Group common stockholders	55.2	46.2	89.0	85.2
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	1,926.1	1,434.6	3,793.6	2,823.0
Cost of sales	1,659.4	1,234.2	3,258.1	2,420.8
Gross profit	266.7	200.4	535.5	402.2
Selling, general and administrative expenses	204.8	156.1	400.2	308.0
Depreciation	7.4	5.8	14.3	11.7
Operating income	54.5	38.5	121.0	82.5
Floor plan interest expense	(3.8)	(3.2)	(7.5)	(6.3)
Other interest expense	(4.6)	(5.4)	(9.4)	(9.5)
Equity in earnings of affiliates	1.5	2.0	2.4	2.4
Income from continuing operations before income taxes	47.6	31.9	106.5	69.1
Income taxes	(15.4)	(8.9)	(29.4)	(17.3)
Income from continuing operations	32.2	23.0	77.1	51.8
(Loss) income from discontinued operations, net of tax	(7.6)	(1.0)	(13.2)	(1.4)
Net income	24.6	22.0	63.9	50.4
Other Comprehensive Income (Loss), Net of Taxes	16.9	1.5	26.1	(36.3)
Comprehensive Income	41.5	23.5	90.0	14.1
Less: Comprehensive income attributable to the non-controlling interests	0.9	0.4	1.1	1.3
Comprehensive income attributable to Penske Automotive Group common stockholders	$ 40.6	$ 23.1	$ 88.9	$ 12.8