Summary of Quarterly Financial Data (Unaudited) (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Quarterly Financial Data
Total revenues	$ 3,371,252	$ 3,329,854	$ 3,306,021	$ 3,156,390	$ 2,858,467	$ 2,832,517	$ 2,767,068	$ 2,669,440	$ 13,163,517	$ 11,127,492	$ 9,943,350
Gross profit	515,113	500,334	503,642	493,859	440,493	449,946	445,304	426,079	2,012,948	1,761,822	1,585,271
Net income	49,236	41,313	49,612	47,006	48,157	56,045	40,059	33,997	187,167	178,258	109,347
Net income attributable to Penske Automotive Group common stockholders	$ 48,599	$ 41,031	$ 49,092	$ 46,818	$ 47,687	$ 55,707	$ 39,560	$ 33,927	$ 185,540	$ 176,881	$ 108,281
Diluted earnings per share attributable to Penske Automotive Group common stockholders (in dollars per share)	$ 0.54	$ 0.45	$ 0.54	$ 0.52	$ 0.53	$ 0.61	$ 0.43	$ 0.37	$ 2.05	$ 1.94	$ 1.18