RECEIVABLES (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
RECEIVABLES
Trade	$ 116,218	$ 42,055
Unbilled revenue	17,857	1,296
Other	1,890	810
Total receivables	135,965	44,161
Allowance for doubtful accounts	(704)	(525)	(468)
Receivables, net	135,261	43,636
Change in the allowance for doubtful accounts receivable
Balance at Beginning of Period	525	468	311
Charged (Credited) to Costs and Expenses	1,391	138	137
Recoveries (Deductions/ Write-offs)	(1,211)	(70)	17
Adjustments	(1)	(11)	3
Balance at End of Period	$ 704	$ 525	$ 468