Guarantor/Non-Guarantor Condensed Consolidated Financial Statements - Statements of Operations (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues	$ 229,773	$ 187,651	$ 691,575	$ 512,285
Costs and expenses:
Operating costs	153,583	116,824	439,670	328,505
Depreciation and amortization	42,067	32,992	120,429	97,672
General and administrative	21,269	17,705	64,677	48,086
Intercompany leasing	0	0	0	0
Bad debt expense (recovery)	(368)	322	(515)	377
Impairment of equipment	0	484	1,032	484
Total costs and expenses	216,551	168,327	625,293	475,124
Income from operations	13,222	19,324	66,282	37,161
Other (expense) income:
Equity in earnings of subsidiaries	0	0	0	0
Interest expense	(9,453)	(6,137)	(26,658)	(21,659)
Other	307	(1,193)	1,259	(6,956)
Total other expense	(9,146)	(7,330)	(25,399)	(28,615)
Income (loss) before income taxes	4,076	11,994	40,883	8,546
Income tax (expense) benefit	(1,461)	(5,250)	(14,411)	(4,187)
Net income (loss)	2,615	6,744	26,472	4,359
Parent [Member]
Revenues	0	0	0	0
Costs and expenses:
Operating costs	0	0	0	0
Depreciation and amortization	201	198	658	685
General and administrative	5,653	4,983	16,713	13,876
Intercompany leasing	0	0	0	0
Bad debt expense (recovery)	0	0	0	0
Impairment of equipment		0	0	0
Total costs and expenses	5,854	5,181	17,371	14,561
Income from operations	(5,854)	(5,181)	(17,371)	(14,561)
Other (expense) income:
Equity in earnings of subsidiaries	11,274	13,663	52,794	26,164
Interest expense	(9,440)	(6,083)	(26,648)	(21,487)
Other	477	(73)	337	384
Total other expense	2,311	7,507	26,483	5,061
Income (loss) before income taxes	(3,543)	2,326	9,112	(9,500)
Income tax (expense) benefit	6,158	4,418	17,360	13,859
Net income (loss)	2,615	6,744	26,472	4,359
Guarantor Subsidiaries [Member]
Revenues	191,753	159,662	575,927	430,820
Costs and expenses:
Operating costs	125,295	95,021	356,880	265,933
Depreciation and amortization	35,727	29,653	102,216	87,782
General and administrative	12,780	12,132	40,151	32,502
Intercompany leasing	(1,215)	(1,215)	(3,645)	(3,645)
Bad debt expense (recovery)	(412)	322	(687)	377
Impairment of equipment		484	1,032	484
Total costs and expenses	172,175	136,397	495,947	383,433
Income from operations	19,578	23,265	79,980	47,387
Other (expense) income:
Equity in earnings of subsidiaries	(441)	(642)	3,820	(3,079)
Interest expense	(26)	(58)	(23)	(187)
Other	210	220	710	671
Total other expense	(257)	(480)	4,507	(2,595)
Income (loss) before income taxes	19,321	22,785	84,487	44,792
Income tax (expense) benefit	(8,047)	(9,122)	(31,693)	(18,628)
Net income (loss)	11,274	13,663	52,794	26,164
Non-Guarantor Subsidiaries [Member]
Revenues	38,020	27,989	115,648	81,465
Costs and expenses:
Operating costs	28,288	21,803	82,790	62,572
Depreciation and amortization	6,139	3,141	17,555	9,205
General and administrative	2,974	698	8,227	2,032
Intercompany leasing	1,215	1,215	3,645	3,645
Bad debt expense (recovery)	44	0	172	0
Impairment of equipment		0	0	0
Total costs and expenses	38,660	26,857	112,389	77,454
Income from operations	(640)	1,132	3,259	4,011
Other (expense) income:
Equity in earnings of subsidiaries	0	0	0	0
Interest expense	13	4	13	15
Other	(242)	(1,232)	626	(7,687)
Total other expense	(229)	(1,228)	639	(7,672)
Income (loss) before income taxes	(869)	(96)	3,898	(3,661)
Income tax (expense) benefit	428	(546)	(78)	582
Net income (loss)	(441)	(642)	3,820	(3,079)
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)	(414)	(324)
Intercompany leasing	0	0	0	0
Bad debt expense (recovery)	0	0	0	0
Impairment of equipment		0	0	0
Total costs and expenses	(138)	(108)	(414)	(324)
Income from operations	138	108	414	324
Other (expense) income:
Equity in earnings of subsidiaries	(10,833)	(13,021)	(56,614)	(23,085)
Interest expense	0	0	0	0
Other	(138)	(108)	(414)	(324)
Total other expense	(10,971)	(13,129)	(57,028)	(23,409)
Income (loss) before income taxes	(10,833)	(13,021)	(56,614)	(23,085)
Income tax (expense) benefit	0	0	0	0
Net income (loss)	$ (10,833)	$ (13,021)	$ (56,614)	$ (23,085)