Consolidated Statements Of Income - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Operating revenues	$ 508,676	$ 534,448	$ 1,490,159	$ 1,564,746
Operating expenses:
Salaries, wages and benefits	162,862	167,301	479,298	479,142
Fuel	40,638	50,855	112,034	160,996
Supplies and maintenance	41,027	50,283	130,559	144,328
Taxes and licenses	21,540	22,616	64,353	66,459
Insurance and claims	19,106	17,372	59,384	60,034
Depreciation	51,781	49,081	152,849	143,065
Rent and purchased transportation	133,876	122,006	379,155	360,706
Communications and utilities	4,206	3,786	12,110	11,301
Other	4,566	(1,652)	9,303	(4,480)
Total operating expenses	479,602	481,648	1,399,045	1,421,551
Operating income	29,074	52,800	91,114	143,195
Other expense (income):
Interest expense	749	511	1,839	1,569
Interest income	(1,055)	(760)	(3,154)	(2,088)
Other	46	32	148	257
Total other income	(260)	(217)	(1,167)	(262)
Income before income taxes	29,334	53,017	92,281	143,457
Income taxes	10,414	20,941	34,963	56,391
Net income	$ 18,920	$ 32,076	$ 57,318	$ 87,066
Earnings per share:
Basic	$ 0.26	$ 0.45	$ 0.80	$ 1.21
Diluted	0.26	0.44	0.79	1.20
Dividends declared per share	$ 0.060	$ 0.060	$ 0.180	$ 0.160
Weighted-average common shares outstanding:
Basic	72,058	71,890	72,043	71,967
Diluted	72,406	72,478	72,364	72,546