Condensed Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Income Statement [Abstract]
Operating revenues, net	$ 167,136	$ 198,547	$ 331,152	$ 402,744
Expenses:
Direct expenses	152,417	168,828	304,971	338,035
Selling, general and administrative expenses	11,778	12,047	23,451	23,284
Total operating expenses	164,195	180,875	328,422	361,319
Gain on asset dispositions	(4,298)	(66)	(3,939)	(73)
Equity in loss of unconsolidated affiliate	76	106	76	174
Operating income	7,163	17,632	6,593	41,324
Interest expense	7,540	7,155	15,073	14,325
Other income, net	(494)	(567)	(1,109)	(1,029)
Total expenses	7,046	6,588	13,964	13,296
Earnings (loss) before income taxes	117	11,044	(7,371)	28,028
Income tax (benefit) expense	(4,160)	4,590	(2,716)	11,211
Net earnings (loss)	$ 4,277	$ 6,454	$ (4,655)	$ 16,817
Weighted average shares outstanding:
Basic	15,677	15,574	15,650	15,574
Diluted	15,718	15,690	15,650	15,679
Net earnings (loss) per share:
Basic	$ 0.27	$ 0.41	$ (0.30)	$ 1.08
Diluted	$ 0.27	$ 0.41	$ (0.30)	$ 1.07