Condensed Consolidating Financial Information - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Condensed consolidating statement of income
Revenues	$ 5,383.4	$ 5,254.1	$ 10,464.5	$ 10,078.7
Cost of sales	4,566.1	4,482.8	8,872.9	8,583.6
Gross profit	817.3	771.3	1,591.6	1,495.1
Selling, general and administrative expenses	622.0	582.7	1,223.7	1,141.6
Depreciation	23.3	24.5	45.7	45.3
Operating income	172.0	164.1	322.2	308.2
Floor plan interest expense	(15.5)	(13.1)	(29.2)	(25.9)
Other interest expense	(26.4)	(19.5)	(51.4)	(36.7)
Equity in earnings of affiliates	26.8	12.0	40.0	17.5
Income from continuing operations before income taxes	156.9	143.5	281.6	263.1
Income taxes	(50.2)	(47.3)	(91.3)	(86.7)
Income from continuing operations	106.7	96.2	190.3	176.4
Income (loss) from discontinued operations, net of tax	0.2	(1.2)	(0.4)	(1.2)
Net income	106.9	95.0	189.9	175.2
Other comprehensive income (loss), net of tax	40.5	(55.5)	66.6	(54.3)
Comprehensive income	147.4	39.5	256.5	120.9
Less: Comprehensive income attributable to non-controlling interests	2.4	0.8	3.2	3.2
Comprehensive income attributable to Penske Automotive Group common stockholders	145.0	38.7	253.3	117.7
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries	(156.6)	(149.9)	(292.3)	(285.0)
Income from continuing operations before income taxes	(156.6)	(149.9)	(292.3)	(285.0)
Income taxes	50.3	49.9	95.2	94.7
Income from continuing operations	(106.3)	(100.0)	(197.1)	(190.3)
Income (loss) from discontinued operations, net of tax	(0.2)	1.2	0.4	1.3
Net income	(106.5)	(98.8)	(196.7)	(189.0)
Other comprehensive income (loss), net of tax	(37.6)	55.7	(61.1)	56.0
Comprehensive income	(144.1)	(43.1)	(257.8)	(133.0)
Less: Comprehensive income attributable to non-controlling interests	(1.6)	0.7	(2.0)	(0.8)
Comprehensive income attributable to Penske Automotive Group common stockholders	(142.5)	(43.8)	(255.8)	(132.2)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses	6.2	5.2	12.2	11.3
Depreciation	0.4	0.4	0.8	0.8
Operating income	(6.6)	(5.6)	(13.0)	(12.1)
Floor plan interest expense	(1.1)	(0.5)	(2.1)	(1.3)
Other interest expense	(17.8)	(12.3)	(34.3)	(25.6)
Equity in earnings of affiliates	25.2	10.5	37.7	14.7
Equity in earnings of subsidiaries	156.6	149.9	292.3	285.0
Income from continuing operations before income taxes	156.3	142.0	280.6	260.7
Income taxes	(50.2)	(47.3)	(91.3)	(86.7)
Income from continuing operations	106.1	94.7	189.3	174.0
Income (loss) from discontinued operations, net of tax	0.2	(1.2)	(0.4)	(1.3)
Net income	106.3	93.5	188.9	172.7
Other comprehensive income (loss), net of tax	40.5	(55.5)	66.6	(54.3)
Comprehensive income	146.8	38.0	255.5	118.4
Less: Comprehensive income attributable to non-controlling interests	1.6	(0.7)	2.0	0.8
Comprehensive income attributable to Penske Automotive Group common stockholders	145.2	38.7	253.5	117.6
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	3,034.8	2,868.6	5,702.7	5,257.8
Cost of sales	2,550.4	2,429.3	4,781.6	4,435.5
Gross profit	484.4	439.3	921.1	822.3
Selling, general and administrative expenses	344.5	326.3	682.9	622.1
Depreciation	13.2	11.7	25.9	22.5
Operating income	126.7	101.3	212.3	177.7
Floor plan interest expense	(9.7)	(7.7)	(18.1)	(14.4)
Other interest expense	(2.2)	(1.9)	(4.3)	(0.6)
Income from continuing operations before income taxes	114.8	91.7	189.9	162.7
Income taxes	(41.2)	(36.7)	(73.8)	(65.9)
Income from continuing operations	73.6	55.0	116.1	96.8
Income (loss) from discontinued operations, net of tax	0.2	(1.2)	(0.4)	(1.1)
Net income	73.8	53.8	115.7	95.7
Comprehensive income	73.8	53.8	115.7	95.7
Less: Comprehensive income attributable to non-controlling interests		0.1		0.1
Comprehensive income attributable to Penske Automotive Group common stockholders	73.8	53.7	115.7	95.6
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,348.6	2,385.5	4,761.8	4,820.9
Cost of sales	2,015.7	2,053.5	4,091.3	4,148.1
Gross profit	332.9	332.0	670.5	672.8
Selling, general and administrative expenses	271.3	251.2	528.6	508.2
Depreciation	9.7	12.4	19.0	22.0
Operating income	51.9	68.4	122.9	142.6
Floor plan interest expense	(4.7)	(4.9)	(9.0)	(10.2)
Other interest expense	(6.4)	(5.3)	(12.8)	(10.5)
Equity in earnings of affiliates	1.6	1.5	2.3	2.8
Income from continuing operations before income taxes	42.4	59.7	103.4	124.7
Income taxes	(9.1)	(13.2)	(21.4)	(28.8)
Income from continuing operations	33.3	46.5	82.0	95.9
Income (loss) from discontinued operations, net of tax				(0.1)
Net income	33.3	46.5	82.0	95.8
Other comprehensive income (loss), net of tax	37.6	(55.7)	61.1	(56.0)
Comprehensive income	70.9	(9.2)	143.1	39.8
Less: Comprehensive income attributable to non-controlling interests	2.4	0.7	3.2	3.1
Comprehensive income attributable to Penske Automotive Group common stockholders	$ 68.5	$ (9.9)	$ 139.9	$ 36.7