Condensed Consolidating Financial Information (Details 2) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Condensed consolidating statement of income
Revenue	$ 4,921.3	$ 4,960.1	$ 4,920.6	$ 4,482.9	$ 4,425.6	$ 4,396.7	$ 4,384.5	$ 4,025.2	$ 19,284.9	$ 17,232.0	$ 14,482.5
Cost of sales									16,417.4	14,652.8	12,281.5
Gross profit	717.1	729.2	731.3	689.9	660.1	647.6	656.4	615.1	2,867.5	2,579.2	2,201.0
Selling, general and administrative expenses									2,223.0	2,008.6	1,711.6
Depreciation									78.0	70.2	59.6
Operating income									566.5	500.4	429.8
Floor plan interest expense									(44.5)	(46.5)	(43.4)
Other interest expense									(69.4)	(52.8)	(45.3)
Gain on investment										16.0
Equity in earnings of affiliates									39.3	40.8	30.7
Income from continuing operations before income taxes									491.9	457.9	371.8
Income taxes									(158.0)	(153.1)	(123.3)
Income from continuing operations									333.9	304.8	248.5
(Loss) income from discontinued operations, net of tax									(3.5)	(14.7)	(2.8)
Net income	$ 71.3	$ 87.5	$ 95.7	$ 75.9	$ 73.2	$ 75.1	$ 73.9	$ 67.9	330.4	290.1	245.7
Other comprehensive income (loss), net of tax									(70.3)	(66.2)	18.9
Comprehensive income									260.1	223.9	264.6
Less: Comprehensive income attributable to non-controlling interests									3.2	2.1	2.0
Comprehensive income attributable to Penske Automotive Group common stockholders									256.9	221.8	262.6
Eliminations
Condensed consolidating statement of income
Equity in earnings of subsidiaries									(527.0)	(473.2)	(406.1)
Income from continuing operations before income taxes									(527.0)	(473.2)	(406.1)
Income taxes									170.5	157.9	135.0
Income from continuing operations									(356.5)	(315.3)	(271.1)
(Loss) income from discontinued operations, net of tax									4.0	16.8	4.6
Net income									(352.5)	(298.5)	(266.5)
Other comprehensive income (loss), net of tax									62.9	62.5	(9.8)
Comprehensive income									(289.6)	(236.0)	(276.3)
Less: Comprehensive income attributable to non-controlling interests									1.1	1.4	(0.5)
Comprehensive income attributable to Penske Automotive Group common stockholders									(290.7)	(237.4)	(275.8)
Reportable legal entities | Penske Automotive Group
Condensed consolidating statement of income
Selling, general and administrative expenses									23.6	28.7	21.4
Depreciation									1.6	1.3	1.8
Operating income									(25.2)	(30.0)	(23.2)
Floor plan interest expense									(2.8)	(10.4)	(9.6)
Other interest expense									(45.6)	(29.8)	(26.1)
Gain on investment										16.0
Equity in earnings of affiliates									34.8	36.5	25.5
Equity in earnings of subsidiaries									527.0	473.2	406.1
Income from continuing operations before income taxes									488.2	455.5	372.7
Income taxes									(158.0)	(152.0)	(123.9)
Income from continuing operations									330.2	303.5	248.8
(Loss) income from discontinued operations, net of tax									(4.0)	(16.8)	(4.6)
Net income									326.2	286.7	244.2
Other comprehensive income (loss), net of tax									(70.3)	(66.2)	18.9
Comprehensive income									255.9	220.5	263.1
Less: Comprehensive income attributable to non-controlling interests									(1.1)	(1.4)	0.5
Comprehensive income attributable to Penske Automotive Group common stockholders									257.0	221.9	262.6
Reportable legal entities | Guarantor Subsidiaries
Condensed consolidating statement of income
Revenue									10,152.4	9,589.0	8,534.2
Cost of sales									8,582.4	8,092.5	7,178.5
Gross profit									1,570.0	1,496.5	1,355.7
Selling, general and administrative expenses									1,193.0	1,133.9	1,025.9
Depreciation									42.0	37.8	33.8
Operating income									335.0	324.8	296.0
Floor plan interest expense									(22.0)	(20.7)	(19.5)
Other interest expense									(5.3)	(5.0)	(1.9)
Income from continuing operations before income taxes									307.7	299.1	274.6
Income taxes									(117.4)	(110.3)	(100.4)
Income from continuing operations									190.3	188.8	174.2
(Loss) income from discontinued operations, net of tax									(1.4)	(2.4)	0.9
Net income									188.9	186.4	175.1
Other comprehensive income (loss), net of tax										4.7	4.0
Comprehensive income									188.9	191.1	179.1
Comprehensive income attributable to Penske Automotive Group common stockholders									188.9	191.1	179.1
Reportable legal entities | Non-Guarantor Subsidiaries
Condensed consolidating statement of income
Revenue									9,132.5	7,643.0	5,948.3
Cost of sales									7,835.0	6,560.3	5,103.0
Gross profit									1,297.5	1,082.7	845.3
Selling, general and administrative expenses									1,006.4	846.0	664.3
Depreciation									34.4	31.1	24.0
Operating income									256.7	205.6	157.0
Floor plan interest expense									(19.7)	(15.4)	(14.3)
Other interest expense									(18.5)	(18.0)	(17.3)
Equity in earnings of affiliates									4.5	4.3	5.2
Income from continuing operations before income taxes									223.0	176.5	130.6
Income taxes									(53.1)	(48.7)	(34.0)
Income from continuing operations									169.9	127.8	96.6
(Loss) income from discontinued operations, net of tax									(2.1)	(12.3)	(3.7)
Net income									167.8	115.5	92.9
Other comprehensive income (loss), net of tax									(62.9)	(67.2)	5.8
Comprehensive income									104.9	48.3	98.7
Less: Comprehensive income attributable to non-controlling interests									3.2	2.1	2.0
Comprehensive income attributable to Penske Automotive Group common stockholders									$ 101.7	$ 46.2	$ 96.7