Condensed Consolidating Financial Information - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Condensed consolidating statement of income
Revenues	$ 5,254.1	$ 4,920.6	$ 10,078.7	$ 9,403.5
Cost of sales	4,482.8	4,189.3	8,583.6	7,982.3
Gross profit	771.3	731.3	1,495.1	1,421.2
Selling, general and administrative expenses	582.7	553.1	1,141.6	1,088.9
Depreciation	24.5	19.3	45.3	37.9
Operating income	164.1	158.9	308.2	294.4
Floor plan interest expense	(13.1)	(11.0)	(25.9)	(21.3)
Other interest expense	(19.5)	(16.4)	(36.7)	(32.7)
Equity in earnings of affiliates	12.0	12.0	17.5	18.7
Income from continuing operations before income taxes	143.5	143.5	263.1	259.1
Income taxes	(47.3)	(47.7)	(86.7)	(86.5)
Income from continuing operations	96.2	95.8	176.4	172.6
(Loss) income from discontinued operations, net of tax	(1.2)	(0.1)	(1.2)	(1.0)
Net income	95.0	95.7	175.2	171.6
Other comprehensive income (loss), net of tax	(55.5)	38.3	(54.3)	(16.8)
Comprehensive income	39.5	134.0	120.9	154.8
Less: Comprehensive income attributable to non-controlling interests	0.8	1.5	3.2	1.6
Comprehensive income attributable to Penske Automotive Group common stockholders	38.7	132.5	117.7	153.2
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries	(149.9)	(148.4)	(285.0)	(275.4)
Income from continuing operations before income taxes	(149.9)	(148.4)	(285.0)	(275.4)
Income taxes	49.9	49.7	94.7	92.5
Income from continuing operations	(100.0)	(98.7)	(190.3)	(182.9)
(Loss) income from discontinued operations, net of tax	1.2	0.4	1.3	1.6
Net income	(98.8)	(98.3)	(189.0)	(181.3)
Other comprehensive income (loss), net of tax	55.7	(37.5)	56.0	14.8
Comprehensive income	(43.1)	(135.8)	(133.0)	(166.5)
Less: Comprehensive income attributable to non-controlling interests	0.7	0.2	(0.8)	0.8
Comprehensive income attributable to Penske Automotive Group common stockholders	(43.8)	(136.0)	(132.2)	(167.3)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses	5.2	5.6	11.3	12.3
Depreciation	0.4	0.4	0.8	0.8
Operating income	(5.6)	(6.0)	(12.1)	(13.1)
Floor plan interest expense	(0.5)	(0.7)	(1.3)	(1.4)
Other interest expense	(12.3)	(10.2)	(25.6)	(20.0)
Equity in earnings of affiliates	10.5	10.5	14.7	16.3
Equity in earnings of subsidiaries	149.9	148.4	285.0	275.4
Income from continuing operations before income taxes	142.0	142.0	260.7	257.2
Income taxes	(47.3)	(47.7)	(86.7)	(86.5)
Income from continuing operations	94.7	94.3	174.0	170.7
(Loss) income from discontinued operations, net of tax	(1.2)	(0.4)	(1.3)	(1.6)
Net income	93.5	93.9	172.7	169.1
Other comprehensive income (loss), net of tax	(55.5)	38.3	(54.3)	(16.8)
Comprehensive income	38.0	132.2	118.4	152.3
Less: Comprehensive income attributable to non-controlling interests	(0.7)	(0.2)	0.8	(0.8)
Comprehensive income attributable to Penske Automotive Group common stockholders	38.7	132.4	117.6	153.1
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,868.6	2,609.0	5,257.8	4,957.3
Cost of sales	2,429.3	2,203.6	4,435.5	4,175.2
Gross profit	439.3	405.4	822.3	782.1
Selling, general and administrative expenses	326.3	300.1	622.1	593.3
Depreciation	11.7	10.4	22.5	20.6
Operating income	101.3	94.9	177.7	168.2
Floor plan interest expense	(7.7)	(5.6)	(14.4)	(10.8)
Other interest expense	(1.9)	(1.4)	(0.6)	(2.7)
Income from continuing operations before income taxes	91.7	87.9	162.7	154.7
Income taxes	(36.7)	(34.1)	(65.9)	(62.4)
Income from continuing operations	55.0	53.8	96.8	92.3
(Loss) income from discontinued operations, net of tax	(1.2)	(0.1)	(1.1)	(1.2)
Net income	53.8	53.7	95.7	91.1
Comprehensive income	53.8	53.7	95.7	91.1
Less: Comprehensive income attributable to non-controlling interests	0.1		0.1
Comprehensive income attributable to Penske Automotive Group common stockholders	53.7	53.7	95.6	91.1
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,385.5	2,311.6	4,820.9	4,446.2
Cost of sales	2,053.5	1,985.7	4,148.1	3,807.1
Gross profit	332.0	325.9	672.8	639.1
Selling, general and administrative expenses	251.2	247.4	508.2	483.3
Depreciation	12.4	8.5	22.0	16.5
Operating income	68.4	70.0	142.6	139.3
Floor plan interest expense	(4.9)	(4.7)	(10.2)	(9.1)
Other interest expense	(5.3)	(4.8)	(10.5)	(10.0)
Equity in earnings of affiliates	1.5	1.5	2.8	2.4
Income from continuing operations before income taxes	59.7	62.0	124.7	122.6
Income taxes	(13.2)	(15.6)	(28.8)	(30.1)
Income from continuing operations	46.5	46.4	95.9	92.5
(Loss) income from discontinued operations, net of tax			(0.1)	0.2
Net income	46.5	46.4	95.8	92.7
Other comprehensive income (loss), net of tax	(55.7)	37.5	(56.0)	(14.8)
Comprehensive income	(9.2)	83.9	39.8	77.9
Less: Comprehensive income attributable to non-controlling interests	0.7	1.5	3.1	1.6
Comprehensive income attributable to Penske Automotive Group common stockholders	$ (9.9)	$ 82.4	$ 36.7	$ 76.3