Condensed Consolidating Financial Information (Details 2) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Condensed consolidating statement of income
Revenue	$ 4,904.4	$ 4,370.5	$ 9,375.5	$ 8,385.7
Cost of sales	4,174.8	3,715.7	7,957.2	7,116.9
Gross profit	729.6	654.8	1,418.3	1,268.8
Selling, general and administrative expenses	551.3	502.0	1,085.8	979.2
Depreciation	19.2	17.0	37.8	33.1
Operating income	159.1	135.8	294.7	256.5
Floor plan interest expense	(11.0)	(11.6)	(21.1)	(22.7)
Other interest expense	(16.4)	(12.4)	(32.7)	(24.8)
Equity in earnings of affiliates	12.0	10.9	18.7	16.0
Income from continuing operations before income taxes	143.7	122.7	259.6	225.0
Income taxes	(47.6)	(41.2)	(86.4)	(75.9)
Income from continuing operations	96.1	81.5	173.2	149.1
(Loss) income from discontinued operations, net of tax	(0.4)	(7.6)	(1.6)	(7.3)
Net income	95.7	73.9	171.6	141.8
Other comprehensive income (loss), net of taxes	38.3	18.8	(16.8)	25.0
Comprehensive income	134.0	92.7	154.8	166.8
Less: Comprehensive income attributable to non-controlling interests	1.5	0.9	1.6	1.1
Comprehensive income attributable to Penske Automotive Group common stockholders	132.5	91.8	153.2	165.7
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries	(148.4)	(128.3)	(275.4)	(241.7)
Income from continuing operations before income taxes	(148.4)	(128.3)	(275.4)	(241.7)
Income taxes	49.8	43.4	92.6	82.0
Income from continuing operations	(98.6)	(84.9)	(182.8)	(159.7)
(Loss) income from discontinued operations, net of tax	0.4	7.6	1.6	7.3
Net income	(98.2)	(77.3)	(181.2)	(152.4)
Other comprehensive income (loss), net of taxes	(37.5)	(18.4)	14.8	(25.2)
Comprehensive income	(135.7)	(95.7)	(166.4)	(177.6)
Less: Comprehensive income attributable to non-controlling interests	0.2		0.8	0.2
Comprehensive income attributable to Penske Automotive Group common stockholders	(135.9)	(95.7)	(167.2)	(177.8)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses	5.6	5.9	12.3	11.7
Depreciation	0.4	0.3	0.8	0.6
Operating income	(6.0)	(6.2)	(13.1)	(12.3)
Floor plan interest expense	(0.7)	(2.4)	(1.4)	(4.8)
Other interest expense	(10.2)	(7.4)	(20.0)	(14.5)
Equity in earnings of affiliates	10.5	9.4	16.3	13.6
Equity in earnings of subsidiaries	148.4	128.3	275.4	241.7
Income from continuing operations before income taxes	142.0	121.7	257.2	223.7
Income taxes	(47.6)	(41.2)	(86.4)	(76.0)
Income from continuing operations	94.4	80.5	170.8	147.7
(Loss) income from discontinued operations, net of tax	(0.4)	(7.6)	(1.6)	(7.3)
Net income	94.0	72.9	169.2	140.4
Other comprehensive income (loss), net of taxes	38.3	18.8	(16.8)	25.0
Comprehensive income	132.3	91.7	152.4	165.4
Less: Comprehensive income attributable to non-controlling interests	(0.2)		(0.8)	(0.2)
Comprehensive income attributable to Penske Automotive Group common stockholders	132.5	91.7	153.2	165.6
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenue	2,609.0	2,454.3	4,957.3	4,612.1
Cost of sales	2,203.6	2,064.7	4,175.2	3,875.7
Gross profit	405.4	389.6	782.1	736.4
Selling, general and administrative expenses	300.1	292.8	593.3	570.2
Depreciation	10.4	9.4	20.6	18.3
Operating income	94.9	87.4	168.2	147.9
Floor plan interest expense	(5.6)	(5.3)	(10.8)	(10.3)
Other interest expense	(1.4)	(0.4)	(2.7)	(0.9)
Income from continuing operations before income taxes	87.9	81.7	154.7	136.7
Income taxes	(34.1)	(28.0)	(62.4)	(52.6)
Income from continuing operations	53.8	53.7	92.3	84.1
(Loss) income from discontinued operations, net of tax	(0.2)		(1.3)	5.8
Net income	53.6	53.7	91.0	89.9
Other comprehensive income (loss), net of taxes		1.5		(0.9)
Comprehensive income	53.6	55.2	91.0	89.0
Comprehensive income attributable to Penske Automotive Group common stockholders	53.6	55.2	91.0	89.0
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenue	2,295.4	1,916.2	4,418.2	3,773.6
Cost of sales	1,971.2	1,651.0	3,782.0	3,241.2
Gross profit	324.2	265.2	636.2	532.4
Selling, general and administrative expenses	245.6	203.3	480.2	397.3
Depreciation	8.4	7.3	16.4	14.2
Operating income	70.2	54.6	139.6	120.9
Floor plan interest expense	(4.7)	(3.9)	(8.9)	(7.6)
Other interest expense	(4.8)	(4.6)	(10.0)	(9.4)
Equity in earnings of affiliates	1.5	1.5	2.4	2.4
Income from continuing operations before income taxes	62.2	47.6	123.1	106.3
Income taxes	(15.7)	(15.4)	(30.2)	(29.3)
Income from continuing operations	46.5	32.2	92.9	77.0
(Loss) income from discontinued operations, net of tax	(0.2)	(7.6)	(0.3)	(13.1)
Net income	46.3	24.6	92.6	63.9
Other comprehensive income (loss), net of taxes	37.5	16.9	(14.8)	26.1
Comprehensive income	83.8	41.5	77.8	90.0
Less: Comprehensive income attributable to non-controlling interests	1.5	0.9	1.6	1.1
Comprehensive income attributable to Penske Automotive Group common stockholders	$ 82.3	$ 40.6	$ 76.2	$ 88.9