Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flows from operating activities:
Net loss	$ (9,353)	$ (7,581)
Adjustments to reconcile net loss to net cash provided by (used in) operating activities:
Depreciation and amortization expense	1,077	1,065
Stock-based compensation expense	766	1,148
Unrealized foreign exchange loss	675	639
Non-cash lease expense	288	310
Provision for bad debts on trade receivables	23	0
Non-cash interest expense	175	26
Amortization/accretion on investments	0	(4)
Changes in operating assets and liabilities:
Accounts receivable	2,881	252
Royalty receivable	15	(3)
Inventories	216	(27)
Prepaid expenses and other assets	952	(69)
Accounts payable, accrued expenses and other liabilities	(1,883)	330
Advance on research and development	(310)	(324)
Net cash used in operating activities	(4,478)	(4,238)
Cash flows from investing activities:
Acquisition of property and equipment	(1,477)	(757)
Maturity of investments	0	7,250
Net cash (used in) provided by investing activities	(1,477)	6,493
Cash flows from financing activities:
Net proceeds from issuance of common stock	1,141	0
Net cash provided by financing activities	1,141	0
Foreign exchange effect on cash and cash equivalents	(62)	(19)
(Decrease) increase in cash, cash equivalents and restricted cash	(4,876)	2,236
Cash, cash equivalents and restricted cash beginning of period	26,856	16,842
Cash, cash equivalents and restricted cash end of period	21,980	19,078
Supplemental information:
Cash paid for interest	346	331
Noncash Investing and Financing Items [Abstract]
Operating leases right-of-use assets obtained in exchange for lease obligations	$ 0	$ 6,988