Condensed Consolidated Statements of Earnings (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Operating revenues, excluding fuel surcharge revenues	$ 1,461,768	$ 1,426,654
Fuel surcharge revenues	167,390	102,058
Total operating revenues	1,629,158	1,528,712
Operating expenses:
Rents and purchased transportation	806,439	740,402
Salaries, wages and employee benefits	380,311	362,511
Depreciation and amortization	92,189	88,352
Fuel and fuel taxes	80,646	59,414
Operating supplies and expenses	58,022	54,537
General and administrative expenses, net of asset dispositions	23,481	21,833
Insurance and claims	23,005	17,428
Operating taxes and licenses	10,680	11,126
Communication and utilities	4,996	5,219
Total operating expenses	1,479,769	1,360,822
Operating income	149,389	167,890
Net interest expense	6,817	6,442
Earnings before income taxes	142,572	161,448
Income taxes	39,870	61,350
Net earnings	$ 102,702	$ 100,098
Weighted average basic shares outstanding (in shares)	110,878	113,072
Basic earnings per share (in dollars per share)	$ 0.93	$ 0.89
Weighted average diluted shares outstanding (in shares)	112,026	114,003
Diluted earnings per share (in dollars per share)	$ 0.92	$ 0.88
Dividends declared per common share (in dollars per share)	$ 0.23	$ 0.22