Consolidated Statements of Income and Comprehensive Income (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues:
New and used truck sales	$ 797,291	$ 508,194	$ 1,398,191	$ 997,804
Parts and service	330,982	242,928	639,956	474,407
Lease and rental	44,057	31,358	85,046	61,498
Finance and insurance	5,256	3,838	9,332	6,971
Other	4,875	3,356	8,603	5,782
Total revenue	1,182,461	789,674	2,141,128	1,546,462
Cost of products sold:
New and used truck sales	738,851	473,153	1,296,993	925,727
Parts and service	212,016	152,449	410,719	298,162
Lease and rental	38,245	26,384	74,142	51,097
Total cost of products sold	989,112	651,986	1,781,854	1,274,986
Gross profit	193,349	137,688	359,274	271,476
Selling, general and administrative	149,260	118,628	283,705	220,734
Depreciation and amortization	9,177	7,259	17,995	14,369
Gain (loss) on sale of assets	20	(12)	104	29
Operating income	34,932	11,789	57,678	36,402
Interest expense, net	2,543	2,480	5,674	4,993
Income before taxes	32,389	9,309	52,004	31,409
Provision for income taxes	12,551	3,677	20,152	12,230
Net income	19,838	5,632	31,852	19,179
Earnings per common share:
Basic (in Dollars per share)	$ 0.50	$ 0.14	$ 0.81	$ 0.49
Diluted (in Dollars per share)	$ 0.49	$ 0.14	$ 0.78	$ 0.47
Weighted average shares outstanding:
Basic (in Shares)	39,751	39,552	39,544	39,337
Diluted (in Shares)	40,849	40,581	40,682	40,446
Comprehensive income	$ 20,154	$ 5,785	$ 32,282	$ 19,502