Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016
Cash flows from operating activities
Net loss	$ (29,825)	$ (25,703)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash other expense, net	(1,008)	(253)
Non-cash interest income	(63)	(65)
Depreciation and amortization expense	149	99
Stock-based compensation	2,876	1,405
Deferred income taxes	(683)	(31)
Other, net	105	1
Changes in operating assets and liabilities:
Changes in long-term receivables	12	(6)
Changes in other receivables and prepaid expenses	(3,315)	(3,039)
Changes in accounts payable	4,975	(1,097)
Changes in accrued expenses and other liabilities	(3,460)	3,550
Changes in other non-current liabilities	18	9
Net cash used in operating activities	(30,219)	(25,130)
Cash flows from investing activities
Purchases of plant and equipment and intangible assets	(236)	(307)
Purchases of available-for-sale securities		(14,000)
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	18,000	15,000
Net cash provided by investing activities	17,766	15,693
Cash flows from financing activities
Proceeds from long-term debt	228
Proceeds from exercise of stock options	11	237
Equity offering costs	(1,483)
Net cash provided by (used in) financing activities	(1,244)	237
Effect of Exchange Rate on Cash and Cash Equivalents	1,008	253
Net decrease in cash and cash equivalents	(12,689)	(8,947)
Cash and cash equivalents at beginning of period	32,778	36,446
Cash and cash equivalents at end of period	$ 20,089	$ 27,499