Guarantor/Non Guarantor Condensed Consolidating Financial Statements (Balance Sheet)) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 53,566	$ 73,640
Restricted cash	998	2,008
Receivables, net of allowance	130,881	113,005
Intercompany receivable (payable)	0	0
Inventory	18,898	14,057
Assets held for sale	3,582	6,620
Prepaid expenses and other current assets	7,109	6,229
Total current assets	215,034	215,559
Net property and equipment	524,858	549,623
Investments in subsidiaries	0	0
Deferred income taxes	0	0
Other noncurrent assets	1,658	1,687
Total assets	741,550	766,869	$ 700,102
Current liabilities:
Accounts payable	34,134	29,538
Deferred revenues	1,722	905
Accrued expenses	68,912	54,471
Total current liabilities	104,768	84,914
Long-term debt, less unamortized discount and debt issuance costs	464,552	461,665
Deferred income taxes	3,688	3,151
Other noncurrent liabilities	3,484	7,043
Total liabilities	576,492	556,773
Total shareholders' equity	165,058	210,096	$ 281,398	$ 342,643
Total liabilities and shareholders' equity	741,550	766,869
Eliminations [Member]
Current assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Receivables, net of allowance	196	(42)
Intercompany receivable (payable)	0	0
Inventory	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	0	0
Total current assets	196	(42)
Net property and equipment	0	0
Investments in subsidiaries	(600,065)	(617,022)
Deferred income taxes	(42,585)	(38,028)
Other noncurrent assets	0	0
Total assets	(642,454)	(655,092)
Current liabilities:
Accounts payable	0	0
Deferred revenues	0	0
Accrued expenses	196	(42)
Total current liabilities	196	(42)
Long-term debt, less unamortized discount and debt issuance costs	0	0
Deferred income taxes	(42,585)	(38,028)
Other noncurrent liabilities	0	0
Total liabilities	(42,389)	(38,070)
Total shareholders' equity	(600,065)	(617,022)
Total liabilities and shareholders' equity	(642,454)	(655,092)
Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	0	0
Restricted cash	0	0
Receivables, net of allowance	95,030	93,866
Intercompany receivable (payable)	67,098	49,651
Inventory	9,945	7,741
Assets held for sale	3,582	6,620
Prepaid expenses and other current assets	3,197	3,193
Total current assets	178,852	161,071
Net property and equipment	494,376	521,080
Investments in subsidiaries	25,370	20,095
Deferred income taxes	0	0
Other noncurrent assets	511	788
Total assets	699,109	703,034
Current liabilities:
Accounts payable	26,795	24,174
Deferred revenues	95	97
Accrued expenses	49,640	37,814
Total current liabilities	76,530	62,085
Long-term debt, less unamortized discount and debt issuance costs	0	0
Deferred income taxes	46,273	41,179
Other noncurrent liabilities	1,611	2,843
Total liabilities	124,414	106,107
Total shareholders' equity	574,695	596,927
Total liabilities and shareholders' equity	699,109	703,034
Non-Guarantor Subsidiaries [Member]
Current assets:
Cash and cash equivalents	3,216	3,263
Restricted cash	0	0
Receivables, net of allowance	35,219	19,174
Intercompany receivable (payable)	(39,853)	(26,696)
Inventory	8,953	6,316
Assets held for sale	0	0
Prepaid expenses and other current assets	2,169	1,798
Total current assets	9,704	3,855
Net property and equipment	28,460	26,532
Investments in subsidiaries	0	0
Deferred income taxes	0	0
Other noncurrent assets	551	403
Total assets	38,715	30,790
Current liabilities:
Accounts payable	6,246	5,078
Deferred revenues	1,627	808
Accrued expenses	5,056	4,195
Total current liabilities	12,929	10,081
Long-term debt, less unamortized discount and debt issuance costs	0	0
Deferred income taxes	0	0
Other noncurrent liabilities	416	614
Total liabilities	13,345	10,695
Total shareholders' equity	25,370	20,095
Total liabilities and shareholders' equity	38,715	30,790
Parent [Member]
Current assets:
Cash and cash equivalents	50,350	70,377
Restricted cash	998	2,008
Receivables, net of allowance	436	7
Intercompany receivable (payable)	(27,245)	(22,955)
Inventory	0	0
Assets held for sale	0	0
Prepaid expenses and other current assets	1,743	1,238
Total current assets	26,282	50,675
Net property and equipment	2,022	2,011
Investments in subsidiaries	574,695	596,927
Deferred income taxes	42,585	38,028
Other noncurrent assets	596	496
Total assets	646,180	688,137
Current liabilities:
Accounts payable	1,093	286
Deferred revenues	0	0
Accrued expenses	14,020	12,504
Total current liabilities	15,113	12,790
Long-term debt, less unamortized discount and debt issuance costs	464,552	461,665
Deferred income taxes	0	0
Other noncurrent liabilities	1,457	3,586
Total liabilities	481,122	478,041
Total shareholders' equity	165,058	210,096
Total liabilities and shareholders' equity	$ 646,180	$ 688,137