CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017	Dec. 31, 2017
Cash flows from operating activities:
Net loss	$ (15,510)	$ (21,174)	$ (36,234)	$ (39,219)	$ (61,662)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	2,287	1,811	4,490	3,471	7,677
Asset write-downs and impairment of field equipment	93	59	142	134	241
Share-based compensation to employees	10,206	7,570	18,726	12,131	27,116
Increase in trade receivables	(3,599)	(2,064)	(5,271)	(7,550)	(23,228)
Amortization of discount	(370)	103	2,057	209	252
Decrease (increase) in receivables and prepaid expenses	(1,277)	3,354	(3,111)	(1,461)	1,979
Decrease in inventories	482	803	2,120	403	3,524
Increase in other long-term assets	(278)	(38)	(898)	(294)	(554)
Increase (decrease) in trade payables	1,016	(1,638)	3,229	(5,195)	(1,150)
Increase (decrease) in other payables and accrued expenses	(528)	4,888	(8,828)	3,478	14,460
Increase in employee benefit liabilities, net	1	130	77	239	440
Increase (decrease) in other long-term liabilities	(16)	321	(816)	870	(2,229)
Net cash used in operating activities	(7,493)	(5,875)	(24,317)	(32,784)	(33,134)
Cash flows from investing activities:
Purchase of property and equipment	(854)	(376)	(1,591)	(1,406)	(2,459)
Purchase of field equipment	(604)	(859)	(1,974)	(2,261)	(4,907)
Proceeds from maturity of short-term investments	60,000	60,000	105,000	120,000	120,000
Purchase of short-term investments	(59,384)	(59,352)	(104,134)	(104,006)	(104,006)
Net cash provided by (used in) investing activities	(842)	(587)	(2,699)	12,327	8,628
Cash flows from financing activities:
Proceeds from issuance of shares, net	938	781	938	781	1,540
Proceeds from long-term loan, net			149,150
Proceeds from other long-term loans		19		19	19
Repayment of long-term loan			(100,000)
Repayment of other long-term loan	(24)	(19)	(41)	(37)	(76)
Exercise of options and warrants	10,274	1,286	12,855	1,363	3,685
Net cash provided by financing activities	11,188	2,067	62,902	2,126	5,168
Effect of exchange rate changes on cash and cash equivalents	11	(1)	21	10	8
Increase (decrease) in cash, cash equivalents and restricted cash	2,864	(4,396)	35,907	(18,321)	(19,330)
Cash, cash equivalents and restricted cash at beginning of period	113,761	86,123	80,718	100,048	100,048
Cash, cash equivalents and restricted cash at the end of the period	116,625	81,727	116,625	81,727	80,718
Cash paid during the period for:
Income taxes	8,256	1,500	12,014	4,902	10,286
Interest	$ 3,416	$ 2,533	$ 6,425	$ 5,041	$ 10,162