Guarantor/Non Guarantor Condensed Consolidated Financial Statements (Balance Sheet (Unaudited)) (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Current assets:
Cash and cash equivalents	$ 34,924	$ 27,385	$ 23,733	$ 86,197
Receivables, net of allowance	190,201	176,360
Intercompany receivable (payable)	0	0
Deferred income taxes	10,998	13,092
Inventory	14,117	13,232
Assets held for sale	9,909	0
Prepaid expenses and other current assets	8,925	9,311
Total current assets	269,074	239,380
Net property and equipment	856,541	937,657
Investments in subsidiaries	0	0
Intangible assets, net of accumulated amortization	24,223	32,194
Noncurrent deferred income taxes	2,753	1,156
Other long-term assets	18,998	19,236
Total assets	1,171,589	1,229,623	1,339,776
Current liabilities:
Accounts payable	64,305	43,718
Current portion of long-term debt	27	2,847
Deferred revenues	3,315	699
Accrued expenses	79,545	73,569
Total current liabilities	147,192	120,833
Long-term debt, less current portion	455,053	499,666
Noncurrent deferred income taxes	69,578	84,636
Other long-term liabilities	4,702	6,055
Total liabilities	676,525	711,190
Total shareholders' equity	495,064	518,433	547,680	510,445
Total liabilities and shareholders' equity	1,171,589	1,229,623
Parent [Member]
Current assets:
Cash and cash equivalents	27,688	28,368	18,479	91,932
Receivables, net of allowance	1,641	905
Intercompany receivable (payable)	(24,836)	(24,837)
Deferred income taxes	1,827	1,143
Inventory	0	0
Assets held for sale	0
Prepaid expenses and other current assets	1,217	1,013
Total current assets	7,537	6,592
Net property and equipment	4,179	4,531
Investments in subsidiaries	830,185	939,091
Intangible assets, net of accumulated amortization	0	0
Noncurrent deferred income taxes	111,286	78,486
Other long-term assets	10,122	7,588
Total assets	963,309	1,036,288
Current liabilities:
Accounts payable	735	757
Current portion of long-term debt	0	0
Deferred revenues	0	0
Accrued expenses	11,109	16,368
Total current liabilities	11,844	17,125
Long-term debt, less current portion	455,000	499,586
Noncurrent deferred income taxes	138	0
Other long-term liabilities	513	394
Total liabilities	467,495	517,105
Total shareholders' equity	495,814	519,183
Total liabilities and shareholders' equity	963,309	1,036,288
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	(5,516)	(2,059)	(5,401)	(13,879)
Receivables, net of allowance	151,048	125,979
Intercompany receivable (payable)	55,567	52,671
Deferred income taxes	8,196	8,005
Inventory	7,208	7,415
Assets held for sale	9,909
Prepaid expenses and other current assets	6,554	7,094
Total current assets	232,966	199,105
Net property and equipment	763,994	846,632
Investments in subsidiaries	116,799	120,630
Intangible assets, net of accumulated amortization	24,223	32,194
Noncurrent deferred income taxes	0	0
Other long-term assets	1,955	2,009
Total assets	1,139,937	1,200,570
Current liabilities:
Accounts payable	57,910	37,797
Current portion of long-term debt	27	2,847
Deferred revenues	3,315	699
Accrued expenses	64,063	51,739
Total current liabilities	125,315	93,082
Long-term debt, less current portion	53	80
Noncurrent deferred income taxes	180,726	163,122
Other long-term liabilities	3,658	5,195
Total liabilities	309,752	261,479
Total shareholders' equity	830,185	939,091
Total liabilities and shareholders' equity	1,139,937	1,200,570
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	12,752	1,076	10,655	8,144
Receivables, net of allowance	37,512	49,476
Intercompany receivable (payable)	(30,728)	(27,834)
Deferred income taxes	975	3,944
Inventory	6,909	5,817
Assets held for sale	0
Prepaid expenses and other current assets	1,154	1,204
Total current assets	28,574	33,683
Net property and equipment	89,118	87,244
Investments in subsidiaries	0	0
Intangible assets, net of accumulated amortization	0	0
Noncurrent deferred income taxes	2,753	1,156
Other long-term assets	6,921	9,639
Total assets	127,366	131,722
Current liabilities:
Accounts payable	5,660	5,164
Current portion of long-term debt	0	0
Deferred revenues	0	0
Accrued expenses	4,376	5,462
Total current liabilities	10,036	10,626
Long-term debt, less current portion	0	0
Noncurrent deferred income taxes	0	0
Other long-term liabilities	531	466
Total liabilities	10,567	11,092
Total shareholders' equity	116,799	120,630
Total liabilities and shareholders' equity	127,366	131,722
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0
Receivables, net of allowance	0	0
Intercompany receivable (payable)	(3)	0
Deferred income taxes	0	0
Inventory	0	0
Assets held for sale	0
Prepaid expenses and other current assets	0	0
Total current assets	(3)	0
Net property and equipment	(750)	(750)
Investments in subsidiaries	(946,984)	(1,059,721)
Intangible assets, net of accumulated amortization	0	0
Noncurrent deferred income taxes	(111,286)	(78,486)
Other long-term assets	0	0
Total assets	(1,059,023)	(1,138,957)
Current liabilities:
Accounts payable	0	0
Current portion of long-term debt	0	0
Deferred revenues	0	0
Accrued expenses	(3)	0
Total current liabilities	(3)	0
Long-term debt, less current portion	0	0
Noncurrent deferred income taxes	(111,286)	(78,486)
Other long-term liabilities	0	0
Total liabilities	(111,289)	(78,486)
Total shareholders' equity	(947,734)	(1,060,471)
Total liabilities and shareholders' equity	$ (1,059,023)	$ (1,138,957)