CONDENSED CONSOLIDATING FINANCIAL STATEMENTS - Condensed Consolidating Unaudited Statements Of Cash Flows (Details) (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities	$ 107,268	$ 46,681
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(69,429)	(72,577)
Acquisition of the 50% noncontrolling interest in Geostream	0	(14,600)
Intercompany notes and accounts	0	0
Other investing activities, net	9,389	3,881
Net cash used in investing activities	(60,040)	(83,296)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	(3,573)	0
Repayment of capital lease obligations	0	(379)
Proceeds from borrowings on revolving credit facility	115,000	155,000
Repayments on revolving credit facility	(160,000)	(135,000)
Payment of deferred financing costs	0	(69)
Repurchases of common stock	(2,211)	(3,134)
Intercompany notes and accounts	0	0
Other financing activities, net	(1,221)	(1,501)
Net cash provided by (used in) financing activities	(52,005)	14,917
Effect of changes in exchange rates on cash	(81)	484
Net decrease in cash and cash equivalents	(4,858)	(21,214)
Cash and cash equivalents, beginning of period	28,306	45,949
Cash and cash equivalents, end of period	23,448	24,735
Parent Company
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities	0	0
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	0	0
Acquisition of the 50% noncontrolling interest in Geostream		0
Intercompany notes and accounts	0	0
Other investing activities, net	0	0
Net cash used in investing activities	0	0
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	(3,573)
Repayment of capital lease obligations		0
Proceeds from borrowings on revolving credit facility	115,000	155,000
Repayments on revolving credit facility	(160,000)	(135,000)
Payment of deferred financing costs		(69)
Repurchases of common stock	(2,211)	(3,134)
Intercompany notes and accounts	41,350	(36,539)
Other financing activities, net	(1,221)	(1,501)
Net cash provided by (used in) financing activities	(10,655)	(21,243)
Effect of changes in exchange rates on cash	0	0
Net decrease in cash and cash equivalents	(10,655)	(21,243)
Cash and cash equivalents, beginning of period	23,115	39,617
Cash and cash equivalents, end of period	12,460	18,374
Guarantor Subsidiaries
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities	100,170	45,284
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(66,280)	(69,413)
Acquisition of the 50% noncontrolling interest in Geostream		(14,600)
Intercompany notes and accounts	(41,350)	36,539
Other investing activities, net	9,389	3,881
Net cash used in investing activities	(98,241)	(43,593)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	0
Repayment of capital lease obligations		(379)
Proceeds from borrowings on revolving credit facility	0	0
Repayments on revolving credit facility	0	0
Payment of deferred financing costs		0
Repurchases of common stock	0	0
Intercompany notes and accounts	0	0
Other financing activities, net	0	0
Net cash provided by (used in) financing activities	0	(379)
Effect of changes in exchange rates on cash	0	0
Net decrease in cash and cash equivalents	1,929	1,312
Cash and cash equivalents, beginning of period	788	1,601
Cash and cash equivalents, end of period	2,717	2,913
Non-Guarantor Subsidiaries
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities	7,098	1,397
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	(3,149)	(3,164)
Acquisition of the 50% noncontrolling interest in Geostream		0
Intercompany notes and accounts	0	0
Other investing activities, net	0	0
Net cash used in investing activities	(3,149)	(3,164)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	0
Repayment of capital lease obligations		0
Proceeds from borrowings on revolving credit facility	0	0
Repayments on revolving credit facility	0	0
Payment of deferred financing costs		0
Repurchases of common stock	0	0
Intercompany notes and accounts	0	0
Other financing activities, net	0	0
Net cash provided by (used in) financing activities	0	0
Effect of changes in exchange rates on cash	(81)	484
Net decrease in cash and cash equivalents	3,868	(1,283)
Cash and cash equivalents, beginning of period	4,403	4,731
Cash and cash equivalents, end of period	8,271	3,448
Eliminations
Schedule of Condensed Consolidating Statement of Cash Flows [Line Items]
Net cash provided by operating activities	0	0
CASH FLOWS FROM INVESTING ACTIVITIES:
Capital expenditures	0	0
Acquisition of the 50% noncontrolling interest in Geostream		0
Intercompany notes and accounts	41,350	(36,539)
Other investing activities, net	0	0
Net cash used in investing activities	41,350	(36,539)
Net Cash Provided by (Used in) Financing Activities [Abstract]
Repayments of long-term debt	0
Repayment of capital lease obligations		0
Proceeds from borrowings on revolving credit facility	0	0
Repayments on revolving credit facility	0	0
Payment of deferred financing costs		0
Repurchases of common stock	0	0
Intercompany notes and accounts	(41,350)	36,539
Other financing activities, net	0	0
Net cash provided by (used in) financing activities	(41,350)	36,539
Effect of changes in exchange rates on cash	0	0
Net decrease in cash and cash equivalents	0	0
Cash and cash equivalents, beginning of period	0	0
Cash and cash equivalents, end of period	$ 0	$ 0