Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Revenues:
New and used commercial vehicle sales	$ 2,640,019	$ 3,360,808	$ 3,195,873
Parts and service sales	1,332,356	1,382,447	1,315,694
Lease and rental	208,154	199,867	177,561
Finance and insurance	18,582	21,150	19,988
Other	15,503	15,461	18,240
Total revenue	4,214,614	4,979,733	4,727,356
Cost of products sold:
New and used commercial vehicle sales	2,463,124	3,138,754	2,975,905
Parts and service sales	851,438	879,141	842,438
Operating Leases, Rent Expense	182,040	176,891	152,967
Total cost of products sold	3,496,602	4,194,786	3,971,310
Gross profit	718,012	784,947	756,046
Selling, general and administrative	587,778	619,268	573,670
Depreciation and amortization	51,261	43,859	40,786
Gain (loss) on sale of assets	1,755	(544)	151
Operating income	80,728	121,276	141,741
Interest income (expense):
Interest income	621	490	239
Interest expense	(14,900)	(13,963)	(11,437)
Total interest expense, net	14,279	13,473	11,198
Income before taxes	66,449	107,803	130,543
Provision for income taxes	25,867	41,750	50,586
Net income	$ 40,582	$ 66,053	$ 79,957
Earnings per common share:
Basic (in dollars per share)	$ 1.02	$ 1.64	$ 2.01
Diluted (in dollars per share)	$ 1	$ 1.61	$ 1.96