Guarantor/Non Guarantor Condensed Consolidated Financial Statements (Cash Flows (Unaudited)) (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities:	$ 7,644	$ 139,065
Cash flows from investing activities:
Purchases of property and equipment	(25,584)	(130,390)
Proceeds from sale of property and equipment	2,743	37,803
Proceeds from insurance recoveries	0	227
Net cash used in investing activities	(22,841)	(92,360)
Cash flows from financing activities:
Debt repayments	(500)	(45,003)
Proceeds from issuance of debt	12,000	0
Debt issuance costs	(819)	(999)
Proceeds from exercise of options	183	781
Purchase of treasury stock	(124)	(729)
Intercompany contributions / distributions	0	0
Net cash provided by (used in) financing activities	10,740	(45,950)
Net increase (decrease) in cash and cash equivalents	(4,457)	755
Beginning cash and cash equivalents	14,160	34,924
Ending cash and cash equivalents	9,703	35,679
Eliminations [Member]
Cash flows from financing activities:
Beginning cash and cash equivalents	0
Ending cash and cash equivalents	0
Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities:	44,422	114,977
Cash flows from investing activities:
Purchases of property and equipment	(24,997)	(128,363)
Proceeds from sale of property and equipment	2,689	37,557
Proceeds from insurance recoveries		227
Net cash used in investing activities	(22,308)	(90,579)
Cash flows from financing activities:
Debt repayments	0	(3)
Proceeds from issuance of debt	0
Debt issuance costs	0	0
Proceeds from exercise of options	0	0
Purchase of treasury stock	0	0
Intercompany contributions / distributions	(17,524)	(17,109)
Net cash provided by (used in) financing activities	(17,524)	(17,112)
Net increase (decrease) in cash and cash equivalents	4,590	7,286
Beginning cash and cash equivalents	(5,612)	(5,516)
Ending cash and cash equivalents	(1,022)	1,770
Non-Guarantor Subsidiaries [Member]
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities:	326	16,979
Cash flows from investing activities:
Purchases of property and equipment	(235)	(1,590)
Proceeds from sale of property and equipment	54	224
Proceeds from insurance recoveries		0
Net cash used in investing activities	(181)	(1,366)
Cash flows from financing activities:
Debt repayments	0	0
Proceeds from issuance of debt	0
Debt issuance costs	0	0
Proceeds from exercise of options	0	0
Purchase of treasury stock	0	0
Intercompany contributions / distributions	(70)	(20,805)
Net cash provided by (used in) financing activities	(70)	(20,805)
Net increase (decrease) in cash and cash equivalents	75	(5,192)
Beginning cash and cash equivalents	2,551	12,752
Ending cash and cash equivalents	2,626	7,560
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Cash flows from operating activities:	(37,104)	7,109
Cash flows from investing activities:
Purchases of property and equipment	(352)	(437)
Proceeds from sale of property and equipment	0	22
Proceeds from insurance recoveries		0
Net cash used in investing activities	(352)	(415)
Cash flows from financing activities:
Debt repayments	(500)	(45,000)
Proceeds from issuance of debt	12,000
Debt issuance costs	(819)	(999)
Proceeds from exercise of options	183	781
Purchase of treasury stock	(124)	(729)
Intercompany contributions / distributions	17,594	37,914
Net cash provided by (used in) financing activities	28,334	(8,033)
Net increase (decrease) in cash and cash equivalents	(9,122)	(1,339)
Beginning cash and cash equivalents	17,221	27,688
Ending cash and cash equivalents	$ 8,099	$ 26,349