Guarantor/Non-Guarantor Condensed Consolidated Financial Statements - Statements of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Revenues	$ 229,824	$ 171,285	$ 461,802	$ 324,634
Costs and expenses:
Operating costs	144,314	110,944	286,087	211,681
Depreciation and amortization	39,989	32,424	78,362	64,680
General and administrative	22,265	15,860	43,408	30,381
Intercompany leasing	0	0	0	0
Bad debt expense (recovery)	(56)	139	(147)	55
Impairment of equipment	0	0	1,032	0
Total costs and expenses	206,512	159,367	408,742	306,797
Income from operations	23,312	11,918	53,060	17,837
Other (expense) income:
Equity in earnings of subsidiaries	0	0	0	0
Interest expense	(7,650)	(7,983)	(17,205)	(15,522)
Other	20	754	952	(5,763)
Total other expense	(7,630)	(7,229)	(16,253)	(21,285)
Income (loss) before income taxes	15,682	4,689	36,807	(3,448)
Income tax (expense) benefit	(5,997)	(1,039)	(12,950)	1,063
Net income (loss)	9,685	3,650	23,857	(2,385)
Parent [Member]
Revenues	0	0	0	0
Costs and expenses:
Operating costs	0	0	0	0
Depreciation and amortization	292	212	457	487
General and administrative	5,552	4,762	11,060	8,893
Intercompany leasing	0	0	0	0
Bad debt expense (recovery)	0	0	0	0
Impairment of equipment			0
Total costs and expenses	5,844	4,974	11,517	9,380
Income from operations	(5,844)	(4,974)	(11,517)	(9,380)
Other (expense) income:
Equity in earnings of subsidiaries	17,970	11,694	41,520	12,501
Interest expense	(7,695)	(7,932)	(17,208)	(15,404)
Other	(72)	(75)	(140)	457
Total other expense	10,203	3,687	24,172	(2,446)
Income (loss) before income taxes	4,359	(1,287)	12,655	(11,826)
Income tax (expense) benefit	5,326	4,937	11,202	9,441
Net income (loss)	9,685	3,650	23,857	(2,385)
Guarantor Subsidiaries [Member]
Revenues	193,332	142,043	384,174	271,158
Costs and expenses:
Operating costs	116,644	89,034	231,585	170,912
Depreciation and amortization	33,800	29,011	66,489	58,129
General and administrative	14,339	10,480	27,371	20,370
Intercompany leasing	(1,215)	(1,215)	(2,430)	(2,430)
Bad debt expense (recovery)	(95)	139	(275)	55
Impairment of equipment			1,032
Total costs and expenses	163,473	127,449	323,772	247,036
Income from operations	29,859	14,594	60,402	24,122
Other (expense) income:
Equity in earnings of subsidiaries	(387)	2,590	4,261	(2,437)
Interest expense	43	(56)	3	(129)
Other	250	215	500	451
Total other expense	(94)	2,749	4,764	(2,115)
Income (loss) before income taxes	29,765	17,343	65,166	22,007
Income tax (expense) benefit	(11,795)	(5,649)	(23,646)	(9,506)
Net income (loss)	17,970	11,694	41,520	12,501
Non-Guarantor Subsidiaries [Member]
Revenues	36,492	29,242	77,628	53,476
Costs and expenses:
Operating costs	27,670	21,910	54,502	40,769
Depreciation and amortization	5,897	3,201	11,416	6,064
General and administrative	2,512	726	5,253	1,334
Intercompany leasing	1,199	1,215	2,430	2,430
Bad debt expense (recovery)	39	0	128	0
Impairment of equipment			0
Total costs and expenses	37,317	27,052	73,729	50,597
Income from operations	(825)	2,190	3,899	2,879
Other (expense) income:
Equity in earnings of subsidiaries	0	0	0	0
Interest expense	2	5	0	11
Other	(36)	722	868	(6,455)
Total other expense	(34)	727	868	(6,444)
Income (loss) before income taxes	(859)	2,917	4,767	(3,565)
Income tax (expense) benefit	472	(327)	(506)	1,128
Net income (loss)	(387)	2,590	4,261	(2,437)
Eliminations [Member]
Revenues	0	0	0	0
Costs and expenses:
Operating costs	0	0	0	0
Depreciation and amortization	0	0	0	0
General and administrative	(138)	(108)	(276)	(216)
Intercompany leasing	16	0	0	0
Bad debt expense (recovery)	0	0	0	0
Impairment of equipment			0
Total costs and expenses	(122)	(108)	(276)	(216)
Income from operations	122	108	276	216
Other (expense) income:
Equity in earnings of subsidiaries	(17,583)	(14,284)	(45,781)	(10,064)
Interest expense	0	0	0	0
Other	(122)	(108)	(276)	(216)
Total other expense	(17,705)	(14,392)	(46,057)	(10,280)
Income (loss) before income taxes	(17,583)	(14,284)	(45,781)	(10,064)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	$ (17,583)	$ (14,284)	$ (45,781)	$ (10,064)