Condensed Consolidating Financial Information - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Condensed consolidating statement of income
Revenues	$ 5,152.0	$ 4,960.1	$ 15,230.7	$ 14,363.6
Cost of sales	4,407.8	4,230.9	12,991.4	12,213.2
Gross profit	744.2	729.2	2,239.3	2,150.4
Selling, general and administrative expenses	581.2	563.4	1,722.8	1,652.3
Depreciation	21.5	19.8	66.8	57.7
Operating income	141.5	146.0	449.7	440.4
Floor plan interest expense	(11.9)	(11.4)	(37.8)	(32.7)
Other interest expense	(25.1)	(16.3)	(61.8)	(49.0)
Equity in earnings of affiliates	25.6	11.0	43.1	29.7
Income from continuing operations before income taxes	130.1	129.3	393.2	388.4
Income taxes	(41.7)	(41.7)	(128.4)	(128.2)
Income from continuing operations	88.4	87.6	264.8	260.2
(Loss) income from discontinued operations, net of tax	0.1	(0.1)	(1.1)	(1.1)
Net income	88.5	87.5	263.7	259.1
Other comprehensive income (loss), net of tax	(10.8)	(42.5)	(65.1)	(59.3)
Comprehensive income	77.7	45.0	198.6	199.8
Less: Comprehensive income attributable to non-controlling interests	1.3	1.5	4.5	3.1
Comprehensive income attributable to Penske Automotive Group common stockholders	76.4	43.5	194.1	196.7
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries	(127.8)	(134.8)	(412.8)	(410.2)
Income from continuing operations before income taxes	(127.8)	(134.8)	(412.8)	(410.2)
Income taxes	41.4	43.8	136.1	136.3
Income from continuing operations	(86.4)	(91.0)	(276.7)	(273.9)
(Loss) income from discontinued operations, net of tax	(0.1)	0.1	1.1	1.7
Net income	(86.5)	(90.9)	(275.6)	(272.2)
Other comprehensive income (loss), net of tax	10.2	40.8	66.2	55.6
Comprehensive income	(76.3)	(50.1)	(209.4)	(216.6)
Less: Comprehensive income attributable to non-controlling interests	(0.3)	(0.6)	(1.1)	0.2
Comprehensive income attributable to Penske Automotive Group common stockholders	(76.0)	(49.5)	(208.3)	(216.8)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses	3.9	5.7	15.2	18.0
Depreciation	0.5	0.4	1.3	1.2
Operating income	(4.4)	(6.1)	(16.5)	(19.2)
Floor plan interest expense	(0.7)	(0.7)	(2.0)	(2.1)
Other interest expense	(18.0)	(10.6)	(43.6)	(30.6)
Equity in earnings of affiliates	24.4	11.0	39.1	27.3
Equity in earnings of subsidiaries	127.8	134.8	412.8	410.2
Income from continuing operations before income taxes	129.1	128.4	389.8	385.6
Income taxes	(41.7)	(41.7)	(128.4)	(128.2)
Income from continuing operations	87.4	86.7	261.4	257.4
(Loss) income from discontinued operations, net of tax	0.1	(0.1)	(1.1)	(1.7)
Net income	87.5	86.6	260.3	255.7
Other comprehensive income (loss), net of tax	(10.8)	(42.5)	(65.1)	(59.3)
Comprehensive income	76.7	44.1	195.2	196.4
Less: Comprehensive income attributable to non-controlling interests	0.3	0.6	1.1	(0.2)
Comprehensive income attributable to Penske Automotive Group common stockholders	76.4	43.5	194.1	196.6
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,896.9	2,591.2	8,113.9	7,548.5
Cost of sales	2,457.1	2,197.2	6,856.0	6,372.4
Gross profit	439.8	394.0	1,257.9	1,176.1
Selling, general and administrative expenses	337.3	302.6	955.8	895.9
Depreciation	12.4	10.6	34.8	31.2
Operating income	90.1	80.8	267.3	249.0
Floor plan interest expense	(7.1)	(5.6)	(21.3)	(16.4)
Other interest expense	(2.2)	(1.3)	(2.8)	(4.0)
Income from continuing operations before income taxes	80.8	73.9	243.2	228.6
Income taxes	(32.2)	(29.4)	(97.9)	(91.8)
Income from continuing operations	48.6	44.5	145.3	136.8
(Loss) income from discontinued operations, net of tax	0.1	(0.1)	(1.0)	(1.3)
Net income	48.7	44.4	144.3	135.5
Comprehensive income	48.7	44.4	144.3	135.5
Comprehensive income attributable to Penske Automotive Group common stockholders	48.7	44.4	144.3	135.5
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues	2,255.1	2,368.9	7,116.8	6,815.1
Cost of sales	1,950.7	2,033.7	6,135.4	5,840.8
Gross profit	304.4	335.2	981.4	974.3
Selling, general and administrative expenses	240.0	255.1	751.8	738.4
Depreciation	8.6	8.8	30.7	25.3
Operating income	55.8	71.3	198.9	210.6
Floor plan interest expense	(4.1)	(5.1)	(14.5)	(14.2)
Other interest expense	(4.9)	(4.4)	(15.4)	(14.4)
Equity in earnings of affiliates	1.2		4.0	2.4
Income from continuing operations before income taxes	48.0	61.8	173.0	184.4
Income taxes	(9.2)	(14.4)	(38.2)	(44.5)
Income from continuing operations	38.8	47.4	134.8	139.9
(Loss) income from discontinued operations, net of tax			(0.1)	0.2
Net income	38.8	47.4	134.7	140.1
Other comprehensive income (loss), net of tax	(10.2)	(40.8)	(66.2)	(55.6)
Comprehensive income	28.6	6.6	68.5	84.5
Less: Comprehensive income attributable to non-controlling interests	1.3	1.5	4.5	3.1
Comprehensive income attributable to Penske Automotive Group common stockholders	$ 27.3	$ 5.1	$ 64.0	$ 81.4