Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017
Cash flows from operating activities
Net loss	$ (31,130)	$ (29,825)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash other expense, net	91	(1,008)
Non-cash interest income	(50)	(63)
Depreciation and amortization expense	262	149
Stock-based compensation	2,011	2,876
Deferred income taxes		(683)
Other, net	(5)	105
Changes in operating assets and liabilities:
Changes in long-term receivables	(3)	12
Changes in other receivables and prepaid expenses	(2,510)	(3,315)
Changes in accounts payable	(2,241)	4,975
Changes in accrued expenses and other liabilities	(142)	(3,456)
Changes in other non-current liabilities	33	18
Changes in income tax liabilities	324	(4)
Net cash used in operating activities	(33,360)	(30,219)
Cash flows from investing activities
Purchases of plant and equipment and intangible assets	(168)	(236)
Purchases of term deposits	(115)
Proceeds from sales of property, plant and equipment		2
Proceeds from sales of available-for-sale securities		18,000
Net cash provided by (used in) investing activities	(283)	17,766
Cash flows from financing activities
Proceeds from sale of ordinary shares	22,784
Proceeds from long-term debt	410	228
Proceeds from exercise of stock options		11
Equity transaction costs	(976)	(1,483)
Net cash provided by (used in) financing activities	22,218	(1,244)
Effects of foreign currency translation on cash and cash equivalents	(91)	1,008
Net decrease in cash and cash equivalents	(11,516)	(12,689)
Cash and cash equivalents at beginning of period	86,769	32,778
Cash and cash equivalents at end of period	$ 75,253	$ 20,089