Consolidated Statements of Income - USD ($) $ in Thousands	12 Months Ended
	Dec. 26, 2015	Dec. 27, 2014	Dec. 28, 2013
Revenue	$ 3,321,091	$ 3,184,790	$ 2,664,780
Investment income	1,396	1,381	1,475
Costs and expenses:
Purchased transportation	2,551,343	2,461,143	2,046,927
Commissions to agents	270,260	250,780	211,355
Other operating costs, net of gains on asset sales/dispositions	31,618	25,771	21,568
Insurance and claims	48,754	46,280	50,438
Selling, general and administrative	149,704	150,250	131,710
Depreciation and amortization	29,102	27,575	27,667
Total costs and expenses	3,080,781	2,961,799	2,489,665
Operating income	241,706	224,372	176,590
Interest and debt expense	2,949	3,177	3,211
Income from continuing operations before income taxes	238,757	221,195	173,379
Income taxes	91,068	82,386	64,457
Income from continuing operations	147,689	138,809	108,922
Discontinued operations:
Income from discontinued operations, net of income taxes			4,058
Gain on sale of discontinued operations, net of income taxes			33,029
Income from discontinued operations, net of income taxes			37,087
Net income	$ 147,689	$ 138,809	$ 146,009
Earnings per common share:
Income from continuing operations	$ 3.38	$ 3.09	$ 2.37
Income from discontinued operations			0.81
Earnings per common share	3.38	3.09	3.17
Diluted earnings per share:
Income from continuing operations	3.37	3.07	2.36
Income from discontinued operations			0.80
Diluted earnings per share	$ 3.37	$ 3.07	$ 3.16
Average number of shares outstanding:
Earnings per common share	43,664,000	44,956,000	46,039,000
Diluted earnings per share	43,813,000	45,169,000	46,210,000
Dividends per common share	$ 0.30	$ 1.26	$ 0.35