Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Operating revenues	$ 534,448	$ 551,961	$ 1,564,746	$ 1,586,103
Operating expenses:
Salaries, wages and benefits	167,301	149,206	479,142	428,425
Fuel	50,855	86,820	160,996	270,026
Supplies and maintenance	50,283	48,527	144,328	140,268
Taxes and licenses	22,616	21,420	66,459	63,563
Insurance and claims	17,372	19,789	60,034	59,175
Depreciation	49,081	44,182	143,065	131,878
Rent and purchased transportation	122,006	133,893	360,706	373,778
Communications and utilities	3,786	3,689	11,301	10,597
Other	(1,652)	2,745	(4,480)	932
Total operating expenses	481,648	510,271	1,421,551	1,478,642
Operating income	52,800	41,690	143,195	107,461
Other expense (income):
Interest expense	511	140	1,569	370
Interest income	(760)	(614)	(2,088)	(1,929)
Other	32	43	257	2
Total other income	(217)	(431)	(262)	(1,557)
Income before income taxes	53,017	42,121	143,457	109,018
Income taxes	20,941	16,151	56,391	43,077
Net income	$ 32,076	$ 25,970	$ 87,066	$ 65,941
Earnings per share:
Basic	$ 0.45	$ 0.36	$ 1.21	$ 0.91
Diluted	0.44	0.36	1.20	0.91
Dividends declared per share	$ 0.060	$ 0.050	$ 0.160	$ 0.150
Weighted-average common shares outstanding:
Basic	71,890	71,837	71,967	72,198
Diluted	72,478	72,364	72,546	72,706