CONSOLIDATED CONDENSED STATEMENT OF EQUITY - USD ($) $ in Millions	Total Stockholders' Equity Attributable to Penske Automotive Group	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Non-controlling Interest	Total
Balance at Dec. 31, 2017	$ 2,395.2		$ 532.3	$ 2,009.4	$ (146.5)	$ 32.8	$ 2,428.0
Balance (in shares) at Dec. 31, 2017		85,787,507
Increase (decrease) in stockholders' equity
Adoption of ASC | ASC 606	6.6			6.6			6.6
Equity compensation	13.0		13.0				13.0
Equity compensation (in shares)		328,286
Repurchases of common stock	(55.8)		(55.8)				(55.8)
Repurchases of common stock (in shares)		(1,252,624)
Dividends	(89.7)			(89.7)			(89.7)
Purchase of subsidiary shares from non-controlling interest	(1.4)		(1.4)			(3.1)	(4.5)
Distributions to non-controlling interest						(0.8)	(0.8)
Foreign currency translation	(56.0)				(56.0)	(1.2)	(57.2)
Other	(1.5)		(0.2)		(1.3)	0.8	(0.7)
Net income	372.9			372.9		0.2	373.1
Balance at Sep. 30, 2018	2,583.3		487.9	2,299.2	(203.8)	28.7	2,612.0
Balance (in shares) at Sep. 30, 2018		84,863,169
Balance at Jun. 30, 2018	2,497.2		483.9	2,199.7	(186.4)	28.6	2,525.8
Balance (in shares) at Jun. 30, 2018		84,865,069
Increase (decrease) in stockholders' equity
Equity compensation	4.0		4.0				4.0
Equity compensation (in shares)		(1,900)
Dividends	(30.7)			(30.7)			(30.7)
Distributions to non-controlling interest						(0.1)	(0.1)
Foreign currency translation	(19.5)				(19.5)	(0.1)	(19.6)
Other	2.1				2.1	0.4	2.5
Net income	130.2			130.2		(0.1)	130.1
Balance at Sep. 30, 2018	2,583.3		487.9	2,299.2	(203.8)	28.7	2,612.0
Balance (in shares) at Sep. 30, 2018		84,863,169
Balance at Dec. 31, 2018	2,609.1		477.8	2,365.8	(234.5)	25.6	2,634.7
Balance (in shares) at Dec. 31, 2018		84,546,970
Increase (decrease) in stockholders' equity
Adoption of ASC | ASC 842	5.0			5.0			5.0
Equity compensation	13.5		13.5				13.5
Equity compensation (in shares)		506,793
Repurchases of common stock	(174.1)		(174.1)				(174.1)
Repurchases of common stock (in shares)		(3,986,836)
Dividends	(97.3)			(97.3)			(97.3)
Purchase of subsidiary shares from non-controlling interest						(4.8)	(4.8)
Distributions to non-controlling interest						(0.5)	(0.5)
Foreign currency translation	(53.4)				(53.4)	(0.7)	(54.1)
Other	1.9				1.9	1.0	2.9
Net income	334.2			334.2		(0.4)	333.8
Balance at Sep. 30, 2019	2,638.9		317.2	2,607.7	(286.0)	20.2	2,659.1
Balance (in shares) at Sep. 30, 2019		81,066,927
Balance at Jun. 30, 2019	2,640.5		356.5	2,524.3	(240.3)	20.5	2,661.0
Balance (in shares) at Jun. 30, 2019		81,956,305
Increase (decrease) in stockholders' equity
Equity compensation	4.3		4.3				4.3
Equity compensation (in shares)		132,244
Repurchases of common stock	(43.6)		(43.6)				(43.6)
Repurchases of common stock (in shares)		(1,021,622)
Dividends	(32.8)			(32.8)			(32.8)
Distributions to non-controlling interest						(0.1)	(0.1)
Foreign currency translation	(43.8)				(43.8)	(0.5)	(44.3)
Other	(1.9)				(1.9)	0.4	(1.5)
Net income	116.2			116.2		(0.1)	116.1
Balance at Sep. 30, 2019	$ 2,638.9		$ 317.2	$ 2,607.7	$ (286.0)	$ 20.2	$ 2,659.1
Balance (in shares) at Sep. 30, 2019		81,066,927