Condensed Consolidated Statements of Cash Flows (Unaudited) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Cash flows from operating activities:
Net loss	$ (13,424)	$ (16,360)
Adjustments to reconcile net loss to net cash used in operating activities:
Stock-based compensation expense	1,048	603
Depreciation and amortization	286	256
Gain on sale of fixed assets		(15)
Paid in-kind interest		(13)
Non-cash interest expense	63	61
Change in fair value of contingent consideration liability	800	1,900
Changes in assets and liabilities:
Accounts receivable	491	2,767
Other current assets	(204)	638
Other assets
Accounts payable	(1,757)	402
Accrued expenses	(1,632)	(3,066)
Other current liabilities
Other liabilities	73	81
Net cash used in operating activities	(14,256)	(12,746)
Cash flows from investing activities:
Purchases of property and equipment	(16)	(145)
Proceeds from sale of fixed assets		32
Net cash used in investing activities	(16)	(113)
Cash flows from financing activities:
Net proceeds from issuance of common stock in connection with at-the-market offering	9,524
Proceeds from exercise of stock options		232
Net cash provided by financing activities	9,524	232
Effect of currency rate changes on cash, cash equivalents and restricted cash	(17)	25
Net decrease in cash, cash equivalents, and restricted cash	(4,765)	(12,602)
Cash, cash equivalents, and restricted cash at beginning of period	92,164	140,910
Cash, cash equivalents, and restricted cash at end of period	87,399	128,308
Cash, cash equivalents, and restricted cash information
Cash, cash equivalents, and restricted cash at beginning of period	$ 92,164	$ 140,910