Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Operating activities:
Net loss	$ (14,897)	$ (9,279)
Items not involving cash:
Depreciation and amortization	334	531
Stock-based compensation	1,076	1,006
Unrealized foreign exchange gain	(819)	(2,508)
Changes in operating assets and liabilities:
Accounts receivable	5	(333)
Prepaid expenses, and other current assets	590	(96)
Prepaid expenses, long term	123	462
Accounts payable and accrued expenses	326	1
Deferred revenue		(157)
Net cash used in operating activities	(13,262)	(10,373)
Investing activities:
Purchases of property, plant and equipment	(238)	(205)
Purchase of marketable securities	(22,281)	(15,300)
Proceeds from marketable securities	41,099
Net cash provided by (used in) investing activities	18,580	(15,505)
Financing activities:
Issuance of common shares pursuant to exercise of stock options	177	82
Net cash provided by financing activities	177	82
Effect of exchange rate changes on cash and cash equivalents	500	2,355
Increase (decrease) in cash and cash equivalents	5,995	(23,441)
Cash and cash equivalents, beginning of period	17,095	58,651
Cash and cash equivalents, end of period	23,090	35,210
Supplemental disclosures:
Interest received	457	204
Supplemental disclosures of non-cash transactions:
Fair value of options exercised on a cashless basis	$ 25	$ 4