Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Cash flows from operating activities
Net loss	$ (52,094)	$ (39,703)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash other expense, net	(1,356)	(283)
Non-cash interest income		(102)
Depreciation and amortization expense	295	172
Stock-based compensation	4,538	1,983
Deferred income taxes	1,410	(428)
Other, net	147	36
Changes in operating assets and liabilities:
Changes in long-term receivables		(8)
Changes in other receivables and prepaid expenses	1,554	(4,418)
Changes in accounts payable	2,632	(234)
Changes in accrued expenses and other liabilities	(2,419)	5,251
Changes in other non-current liabilities	27	13
Net cash used in operating activities	(45,266)	(37,721)
Cash flows from investing activities
Purchases of plant and equipment and intangible assets	(1,141)	(456)
Purchases of available-for-sale securities		(14,000)
Purchases of term deposits		(10)
Proceeds from sales of property, plant and equipment	2
Proceeds from maturities of term deposits		15,000
Proceeds from sales of available-for-sale securities	50,500	25,000
Net cash provided by investing activities	49,361	25,534
Cash flows from financing activities
Proceeds from sale of ordinary shares	80,000
Proceeds from long-term debt	228
Proceeds from exercise of stock options	83	243
Equity offering costs	(6,382)
Net cash provided by financing activities	73,929	243
Effects of foreign currency translation on cash and cash equivalents	1,356	282
Net increase (decrease) in cash and cash equivalents	79,380	(11,662)
Cash and cash equivalents at beginning of period	32,778	36,446
Cash and cash equivalents at end of period	$ 112,158	$ 24,784