Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Operating activities:
Net loss	$ (9,279)	$ (7,988)
Items not involving cash:
Depreciation and amortization	531	492
Stock-based compensation	1,006	3,446
Deferred tenant inducements	(32)	(32)
Unrealized foreign exchange (gain) loss	(2,508)	2,353
Changes in operating assets and liabilities:
Accounts receivable	(333)	31
Prepaid expenses, and other current assets	366	221
Accounts payable and accrued expenses	33	(350)
Deferred revenue	(157)	(6,144)
Net cash used in operating activities	(10,373)	(7,971)
Investing activities:
Purchases of property, plant and equipment	(205)	(190)
Purchase of marketable securities	(15,300)
Proceeds from marketable securities		1,818
Net cash provided by (used in) investing activities	(15,505)	1,628
Financing activities:
Proceeds from issuance of common shares	82	213
Net cash provided by financing activities	82	213
Effect of exchange rate changes on cash and cash equivalents	2,355	(1,550)
Decrease in cash and cash equivalents	(23,441)	(7,680)
Cash and cash equivalents, beginning of period	58,651	72,026
Cash and cash equivalents, end of period	35,210	64,346
Supplemental disclosures:
Interest received	204	268
Supplemental disclosures of non-cash transactions:
Fair value of options exercised on a cashless basis	$ 4	$ 189