Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015
Operating activities:
Net loss	$ (16,993)	$ (11,815)
Items not involving cash:
Depreciation and amortization	698	754
Stock-based compensation	1,642	3,255
Deferred tenant inducements	(47)	(47)
Unrealized foreign exchange (gain) loss	(2,011)	5,486
Changes in operating assets and liabilities:
Accounts receivable	(272)	(61)
Prepaid expenses, and other current assets	1,251	(1,385)
Accounts payable and accrued expenses	992	223
Deferred revenue	(157)	(9,266)
Net cash used in operating activities	(14,897)	(12,856)
Investing activities:
Purchases of property, plant and equipment	(251)	(408)
Purchase of marketable securities	(15,365)
Proceeds from marketable securities		10,745
Net cash provided by (used in) investing activities	(15,616)	10,337
Financing activities:
Issuance of common shares pursuant to exercise of stock options	84	240
Issuance of common shares, net of issuance costs (note 7a)	23,832
Net cash provided by financing activities	23,916	240
Effect of exchange rate changes on cash and cash equivalents	2,081	(4,278)
Decrease in cash and cash equivalents	(4,516)	(6,557)
Cash and cash equivalents, beginning of period	58,651	72,026
Cash and cash equivalents, end of period	54,135	65,469
Supplemental disclosures:
Interest received	261	550
Supplemental disclosures of non-cash transactions:
Fair value of options exercised on a cashless basis	$ 168	$ 544