Condensed Consolidating Financial Information - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed consolidating statement of income
Revenues	$ 4,887.8	$ 5,152.0	$ 5,254.1	$ 4,824.6	$ 4,921.3	$ 4,960.1	$ 4,920.6	$ 4,482.9	$ 20,118.5	$ 19,284.9	$ 17,232.0
Cost of sales									17,151.9	16,417.4	14,652.8
Gross profit	727.3	744.2	771.3	723.8	717.1	729.2	731.3	689.9	2,966.6	2,867.5	2,579.2
Selling, general and administrative expenses									2,302.0	2,223.0	2,008.6
Depreciation									89.7	78.0	70.2
Operating income									574.9	566.5	500.4
Floor plan interest expense									(50.9)	(44.5)	(46.5)
Other interest expense									(85.4)	(69.4)	(52.8)
Gain on investment											16.0
Equity in earnings of affiliates									69.5	39.3	40.8
Income from continuing operations before income taxes									508.1	491.9	457.9
Income taxes									(160.7)	(158.0)	(153.1)
Income from continuing operations									347.4	333.9	304.8
(Loss) income from discontinued operations, net of tax									(1.0)	(3.5)	(14.7)
Net income	$ 82.7	$ 88.5	$ 95.0	$ 80.2	$ 71.3	$ 87.5	$ 95.7	$ 75.9	346.4	330.4	290.1
Other comprehensive income (loss), net of tax									(129.0)	(70.3)	(66.2)
Comprehensive income									217.4	260.1	223.9
Less: Comprehensive income attributable to non-controlling interests									2.7	3.2	2.1
Comprehensive income attributable to Penske Automotive Group common stockholders									214.7	256.9	221.8
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries									(523.3)	(527.0)	(473.2)
Income from continuing operations before income taxes									(523.3)	(527.0)	(473.2)
Income taxes									166.6	170.5	157.9
Income from continuing operations									(356.7)	(356.5)	(315.3)
(Loss) income from discontinued operations, net of tax									1.0	4.0	16.8
Net income									(355.7)	(352.5)	(298.5)
Other comprehensive income (loss), net of tax									123.9	62.9	62.5
Comprehensive income									(231.8)	(289.6)	(236.0)
Less: Comprehensive income attributable to non-controlling interests									0.8	1.1	1.4
Comprehensive income attributable to Penske Automotive Group common stockholders									(232.6)	(290.7)	(237.4)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses									19.2	23.6	28.7
Depreciation									1.7	1.6	1.3
Operating income									(20.9)	(25.2)	(30.0)
Floor plan interest expense									(3.0)	(2.8)	(10.4)
Other interest expense									(59.2)	(45.6)	(29.8)
Gain on investment											16.0
Equity in earnings of affiliates									64.6	34.8	36.5
Equity in earnings of subsidiaries									523.3	527.0	473.2
Income from continuing operations before income taxes									504.8	488.2	455.5
Income taxes									(160.7)	(158.0)	(152.0)
Income from continuing operations									344.1	330.2	303.5
(Loss) income from discontinued operations, net of tax									(1.0)	(4.0)	(16.8)
Net income									343.1	326.2	286.7
Other comprehensive income (loss), net of tax									(129.0)	(70.3)	(66.2)
Comprehensive income									214.1	255.9	220.5
Less: Comprehensive income attributable to non-controlling interests									(0.8)	(1.1)	(1.4)
Comprehensive income attributable to Penske Automotive Group common stockholders									214.9	257.0	221.9
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues									10,946.2	10,152.4	9,589.0
Cost of sales									9,251.8	8,582.4	8,092.5
Gross profit									1,694.4	1,570.0	1,496.5
Selling, general and administrative expenses									1,284.4	1,193.0	1,133.9
Depreciation									47.3	42.0	37.8
Operating income									362.7	335.0	324.8
Floor plan interest expense									(29.1)	(22.0)	(20.7)
Other interest expense									(5.1)	(5.3)	(5.0)
Income from continuing operations before income taxes									328.5	307.7	299.1
Income taxes									(124.4)	(117.4)	(110.3)
Income from continuing operations									204.1	190.3	188.8
(Loss) income from discontinued operations, net of tax									(0.9)	(1.4)	(2.4)
Net income									203.2	188.9	186.4
Other comprehensive income (loss), net of tax											4.7
Comprehensive income									203.2	188.9	191.1
Comprehensive income attributable to Penske Automotive Group common stockholders									203.2	188.9	191.1
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenues									9,172.3	9,132.5	7,643.0
Cost of sales									7,900.1	7,835.0	6,560.3
Gross profit									1,272.2	1,297.5	1,082.7
Selling, general and administrative expenses									998.4	1,006.4	846.0
Depreciation									40.7	34.4	31.1
Operating income									233.1	256.7	205.6
Floor plan interest expense									(18.8)	(19.7)	(15.4)
Other interest expense									(21.1)	(18.5)	(18.0)
Equity in earnings of affiliates									4.9	4.5	4.3
Income from continuing operations before income taxes									198.1	223.0	176.5
Income taxes									(42.2)	(53.1)	(48.7)
Income from continuing operations									155.9	169.9	127.8
(Loss) income from discontinued operations, net of tax									(0.1)	(2.1)	(12.3)
Net income									155.8	167.8	115.5
Other comprehensive income (loss), net of tax									(123.9)	(62.9)	(67.2)
Comprehensive income									31.9	104.9	48.3
Less: Comprehensive income attributable to non-controlling interests									2.7	3.2	2.1
Comprehensive income attributable to Penske Automotive Group common stockholders									$ 29.2	$ 101.7	$ 46.2