Condensed Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Income Statement [Abstract]
Operating revenues, net	$ 216,294	$ 200,762	$ 625,510	$ 575,273
Expenses:
Direct expenses	170,531	160,731	499,541	468,428
Selling, general and administrative expenses	10,903	9,785	31,891	28,075
Total operating expenses	181,434	170,516	531,432	496,503
Loss (gain) on asset dispositions	56	(1,399)	1,371	(16,075)
Impairment of assets				421
Equity in (income) loss of unconsolidated affiliate	(319)	(172)	(213)	911
Operating income	35,123	31,817	92,920	93,513
Interest expense	7,084	7,768	22,121	22,434
Loss on debt extinguishment			29,833
Other income, net	(238)	(163)	(498)	(388)
Total expenses	6,846	7,605	51,456	22,046
Earnings before income taxes	28,277	24,212	41,464	71,467
Income tax expense	11,028	10,435	16,168	29,336
Net earnings	$ 17,249	$ 13,777	$ 25,296	$ 42,131
Weighted average shares outstanding:
Basic	15,483	15,474	15,483	15,474
Diluted	15,727	15,639	15,646	15,617
Net earnings per share:
Basic	$ 1.11	$ 0.89	$ 1.63	$ 2.72
Diluted	$ 1.10	$ 0.88	$ 1.62	$ 2.70