Consolidated Statements of Operations (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Income Statement [Abstract]
Operating revenues, net	$ 836,270	$ 856,500	$ 646,686
Expenses:
Direct expenses	670,007	713,090	543,524
Selling, general and administrative expenses	43,171	38,820	39,051
Total operating expenses	713,178	751,910	582,575
(Gain) loss on disposition of assets, net	848	(16,604)	317
Impairments of assets	10,508	1,648
Equity in loss of unconsolidated affiliate	96	262	863
Operating income	111,640	119,284	62,931
Interest expense	29,510	29,756	29,533
Loss on debt extinguishment	29,833
Other (income),net	(818)	(613)	(651)
Total expenses	58,525	29,143	28,882
Earnings before income taxes	53,115	90,141	34,049
Income tax expense	20,427	31,185	15,992
Net earnings	$ 32,688	$ 58,956	$ 18,057
Earnings per share:
Basic	$ 2.11	$ 3.81	$ 1.17
Diluted	$ 2.08	$ 3.77	$ 1.17
Weighted average shares outstanding:
Basic	15,483	15,474	15,418
Diluted	15,685	15,639	15,488