Guarantor/Non-Guarantor Condensed Consolidated Financial Statements - Balance Sheet (Unaudited) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Current assets:
Cash and cash equivalents	$ 23,733	$ 86,197	$ 22,011	$ 40,379	$ 40,379
Receivables, net of allowance	158,844	145,234
Intercompany receivable (payable)	0	0
Deferred income taxes	11,058	15,433
Inventory	12,111	11,184
Prepaid expenses and other current assets	13,040	11,564
Total current assets	218,786	269,612
Net property and equipment	1,014,340	793,956
Investments in subsidiaries	0	0
Intangible assets, net of amortization	43,843	52,680
Goodwill	41,683	41,683
Noncurrent deferred income taxes	5,519	735
Other long-term assets	15,605	14,088
Total assets	1,339,776	1,172,754	841,343
Current liabilities:
Accounts payable	83,823	66,440
Current portion of long-term debt	872	872
Deferred revenues	3,880	3,966
Accrued expenses	67,975	68,402
Total current liabilities	156,550	139,680
Long-term debt, less current portion	518,725	418,728
Noncurrent deferred income taxes	108,838	94,745
Other long-term liabilities	7,983	9,156
Total liabilities	792,096	662,309
Total shareholders' equity	547,680	510,445	396,333	421,448
Total liabilities and shareholders' equity	1,339,776	1,172,754
Parent [Member]
Current assets:
Cash and cash equivalents	18,479	91,932	15,737	33,352
Receivables, net of allowance	440	(2)
Intercompany receivable (payable)	(124,516)	(122,552)
Deferred income taxes	869	1,408
Inventory	0	0
Prepaid expenses and other current assets	655	285
Total current assets	(104,073)	(28,929)
Net property and equipment	3,474	1,605
Investments in subsidiaries	1,122,814	932,237
Intangible assets, net of amortization	68	171
Goodwill	0	0
Noncurrent deferred income taxes	51,834	30,835
Other long-term assets	9,582	11,949
Total assets	1,083,699	947,868
Current liabilities:
Accounts payable	1,558	1,090
Current portion of long-term debt	0	0
Deferred revenues	0	0
Accrued expenses	14,905	16,779
Total current liabilities	16,463	17,869
Long-term debt, less current portion	518,618	417,747
Noncurrent deferred income taxes	(4)	921
Other long-term liabilities	192	137
Total liabilities	535,269	436,674
Total shareholders' equity	548,430	511,194
Total liabilities and shareholders' equity	1,083,699	947,868
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	10,655	8,144	8,114	9,743
Receivables, net of allowance	29,128	32,724
Intercompany receivable (payable)	(22,136)	(9,033)
Deferred income taxes	2,027	5,381
Inventory	6,155	6,651
Prepaid expenses and other current assets	3,222	4,975
Total current assets	29,051	48,842
Net property and equipment	90,223	117,422
Investments in subsidiaries	0	0
Intangible assets, net of amortization	0	33,680
Goodwill	0	41,683
Noncurrent deferred income taxes	5,519	735
Other long-term assets	3,683	15
Total assets	128,476	242,377
Current liabilities:
Accounts payable	5,437	8,200
Current portion of long-term debt	0	22
Deferred revenues	1,926	2,669
Accrued expenses	4,472	6,631
Total current liabilities	11,835	17,522
Long-term debt, less current portion	0	131
Noncurrent deferred income taxes	0	0
Other long-term liabilities	2,225	3,523
Total liabilities	14,060	21,176
Total shareholders' equity	114,416	221,201
Total liabilities and shareholders' equity	128,476	242,377
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	(5,401)	(13,879)	(1,840)	(2,716)
Receivables, net of allowance	129,570	112,531
Intercompany receivable (payable)	146,652	131,585
Deferred income taxes	8,162	8,644
Inventory	5,956	4,533
Prepaid expenses and other current assets	9,163	6,304
Total current assets	294,102	249,718
Net property and equipment	921,393	675,679
Investments in subsidiaries	114,416	221,201
Intangible assets, net of amortization	43,775	18,829
Goodwill	41,683	0
Noncurrent deferred income taxes	0	0
Other long-term assets	2,340	2,124
Total assets	1,417,709	1,167,551
Current liabilities:
Accounts payable	76,828	57,150
Current portion of long-term debt	872	850
Deferred revenues	1,954	1,297
Accrued expenses	48,892	45,012
Total current liabilities	128,546	104,309
Long-term debt, less current portion	107	850
Noncurrent deferred income taxes	160,676	124,659
Other long-term liabilities	5,566	5,496
Total liabilities	294,895	235,314
Total shareholders' equity	1,122,814	932,237
Total liabilities and shareholders' equity	1,417,709	1,167,551
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0	0	0
Receivables, net of allowance	(294)	(19)
Intercompany receivable (payable)	0	0
Deferred income taxes	0	0
Inventory	0	0
Prepaid expenses and other current assets	0	0
Total current assets	(294)	(19)
Net property and equipment	(750)	(750)
Investments in subsidiaries	(1,237,230)	(1,153,438)
Intangible assets, net of amortization	0	0
Goodwill	0	0
Noncurrent deferred income taxes	(51,834)	(30,835)
Other long-term assets	0	0
Total assets	(1,290,108)	(1,185,042)
Current liabilities:
Accounts payable	0	0
Current portion of long-term debt	0	0
Deferred revenues	0	0
Accrued expenses	(294)	(20)
Total current liabilities	(294)	(20)
Long-term debt, less current portion	0	0
Noncurrent deferred income taxes	(51,834)	(30,835)
Other long-term liabilities	0	0
Total liabilities	(52,128)	(30,855)
Total shareholders' equity	(1,237,980)	(1,154,187)
Total liabilities and shareholders' equity	$ (1,290,108)	$ (1,185,042)