CONDENSED CONSOLIDATED STATEMENTS OF OPERATIONS (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Income Statement [Abstract]
Operating revenues, net	$ 212,145	$ 195,543	$ 409,216	$ 374,511
Expenses:
Direct expenses	170,357	159,494	329,010	307,697
Selling, general and administrative expenses	11,660	10,024	20,988	18,290
Total operating expenses	182,017	169,518	349,998	325,987
Loss (gain) on disposal of assets	242	(14,701)	1,315	(14,676)
Impairment of assets		421	0	421
Equity in loss of unconsolidated affiliate	65	596	106	1,083
Operating income	29,821	39,709	57,797	61,696
Interest expense	7,673	7,257	15,037	14,666
Loss on debt extinguishment	617		29,833
Other income, net	(169)	(73)	(260)	(225)
Total expenses	8,121	7,184	44,610	14,441
Earnings before income taxes	21,700	32,525	13,187	47,255
Income tax expense	8,332	13,009	5,140	18,901
Net earnings	$ 13,368	$ 19,516	$ 8,047	$ 28,354
Weighted average shares outstanding:
Basic	15,482	15,474	15,482	15,474
Diluted	15,696	15,674	15,595	15,673
Net earnings per share:
Basic	$ 0.86	$ 1.26	$ 0.52	$ 1.83
Diluted	$ 0.85	$ 1.25	$ 0.52	$ 1.81