Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Cash flows from operating activities:
Net loss	$ (61,662)	$ (131,845)	$ (111,581)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	7,677	5,652	3,153
Asset write-downs and impairment of field equipment	241	6,446	46
Increase in accrued interest expense			672
Share-based compensation to employees	27,116	22,139	11,860
Excess tax benefits from share-based award activity		(698)
Increase in trade receivables, net	(23,228)	(6,339)
Amortization of discount, net	252	155	329
Decrease (increase) in receivables and prepaid expenses	1,979	243	(5,088)
Decrease (increase) in inventories	3,524	(11,955)	(10,148)
Increase in other long-term assets	(554)	(692)	(381)
Increase (decrease) in trade payables	(1,150)	1,601	6,961
Increase in other payables and accrued expenses	14,460	6,647	3,579
Increase in employee benefit liabilities, net	440	97	133
Increase (decrease) in other long-term liabilities	(2,229)	957	581
Net cash used in operating activities	(33,134)	(107,592)	(99,884)
Cash flows from investing activities:
Purchase of property and equipment	(2,459)	(5,674)	(4,667)
Purchase of field equipment	(4,907)	(11,990)	(5,604)
Increase in restricted cash	(1,858)	(180)	(26)
Proceeds from maturity of short-term investments	120,000	270,000	104,000
Purchase of short-term investments	(104,006)	(239,341)	(208,998)
Net cash provided by (used in) investing activities	6,770	12,815	(115,295)
Cash flows from financing activities:
Proceeds from issuance of shares, net	1,540	616	252,133
Proceeds from long-term loan, net		72,887	22,886
Excess tax benefits from share-based award activity		698
Proceeds from issuance of other long-term loans	19
Repayment of other long-term loans	(76)	(70)	(63)
Exercise of options and warrants	3,685	993	2,038
Purchase of shares in respect of settlement			(5)
Net cash provided by financing activities	5,168	75,124	276,989
Effect of exchange rate changes on cash and cash equivalents	8	10
Increase (decrease) in cash and cash equivalents	(21,188)	(19,643)	61,810
Cash and cash equivalents at the beginning of the year	99,780	119,423	57,613
Cash and cash equivalents at the end of the year	78,592	99,780	119,423
Cash paid during the year for:
Income taxes	10,286	9,447	1,489
Interest	$ 10,162	$ 6,595	$ 1,688