Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenues:
New and used commercial vehicle sales	$ 3,360,808	$ 3,195,873	$ 2,239,847
Parts and service sales	1,382,447	1,315,694	988,317
Lease and rental	199,867	177,561	129,638
Finance and insurance	21,150	19,988	15,320
Other	15,461	18,240	11,583
Total revenue	4,979,733	4,727,356	3,384,705
Cost of products sold:
New and used commercial vehicle sales	3,138,754	2,975,905	2,083,439
Parts and service sales	879,141	842,438	620,030
Lease and rental	176,891	152,967	109,222
Total cost of products sold	4,194,786	3,971,310	2,812,691
Gross profit	784,947	756,046	572,014
Selling, general and administrative	619,268	573,670	450,340
Depreciation and amortization	43,859	40,786	29,925
(Loss) gain on sale of assets	(544)	151	5
Operating income	121,276	141,741	91,754
Interest income (expense):
Interest income	490	239	41
Interest expense	(13,963)	(11,437)	(10,734)
Total interest expense, net	13,473	11,198	10,693
Income before taxes	107,803	130,543	81,061
Provision for income taxes	41,750	50,586	31,844
Net income	$ 66,053	$ 79,957	$ 49,217
Earnings per common share - Basic:
Net income (in dollars per share)	$ 1.64	$ 2.01	$ 1.25
Earnings per common share - Diluted:
Net income (in dollars per share)	$ 1.61	$ 1.96	$ 1.22