CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Cash flows from operating activities:
Net loss	$ (11,498)	$ (33,628)	$ (50,717)	$ (109,677)	$ (131,845)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization	2,053	1,553	5,524	4,063	5,652
Asset write-downs and impairment of field equipment	72	10	206	6,440	6,446
Increase in accrued interest expense		222		222
Share-based compensation to employees	8,629	5,626	20,760	16,719	22,139
Excess tax benefits from share-based award activity					(698)
Increase in trade receivables	(9,112)		(16,661)		(6,339)
Amortization of discount	17	81	226	25	155
Decrease (increase) in receivables and prepaid expenses	5,986	694	4,525	(1,514)	243
Decrease (increase) in inventories	504	(2,757)	907	(10,378)	(11,955)
Increase in other long-term assets	(238)	(526)	(532)	(804)	(692)
Increase (decrease) in trade payables	983	(6,765)	(4,213)	(2,621)	1,601
Increase in other payables and accrued expenses	4,830	1,651	8,308	2,407	6,647
Increase in employee benefit liabilities, net	113	80	352	350	97
Increase in other long-term liabilities	208	263	1,079	901	957
Net cash provided by (used in) operating activities	2,547	(33,496)	(30,236)	(93,867)	(107,592)
Cash flows from investing activities:
Purchase of property and equipment	(544)	(1,715)	(1,951)	(5,055)	(5,674)
Purchase of field equipment	(1,208)	(3,113)	(3,469)	(9,213)	(11,990)
Decrease (increase) in restricted cash	(592)	27	(1,861)	15	(180)
Proceeds from maturity of short-term investments		120,000	120,000	270,000	270,000
Purchase of short-term investments		(119,613)	(104,006)	(239,341)	(239,341)
Net cash provided by (used in) investing activities	(2,344)	(4,414)	8,713	16,406	12,815
Cash flows from financing activities:
Proceeds from issuance of shares, net			781		616
Proceeds from long-term loan, net		72,870	19	72,887	72,887
Excess tax benefits from share-based award activity					698
Repayment of other long-term loan	(19)	(17)	(56)	(52)	(70)
Exercise of options and warrants	1,732		3,095	961	993
Net cash provided by financing activities	1,713	72,853	3,839	73,796	75,124
Effect of exchange rate changes on cash and cash equivalents	(2)	8	8	64	10
Increase (decrease) in cash and cash equivalents	1,914	34,951	(17,676)	(3,601)	(19,643)
Cash and cash equivalents at the beginning of the period	80,190	80,871	99,780	119,423	119,423
Cash and cash equivalents at the end of the period	82,104	115,822	82,104	115,822	99,780
Cash paid during the period for:
Income taxes	2,335	4,624	7,237	7,793	9,447
Interest	$ 2,561	$ 1,880	$ 7,603	$ 3,813	$ 6,595