Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income [Member]	Accumulated Deficit [Member]
Beginning balances at Dec. 31, 2017	$ 119,309	$ 32	$ 186,522	$ 958	$ (68,203)
Beginning balance, shares at Dec. 31, 2017		30,509,522
Issuance of common stock upon at the market offerings, net	493		493
Issuance of common stock upon at The market offering, net, shares		46,900
Issuance of common stock for settlement of RSUs, shares		11,250
Net Issuance of common stock upon cashless exercise of stock options, shares		28,655
Issuance of common stock upon exercise of stock options	3		3
Issuance of common stock upon exercise of stock options, shares		6,000
Issuance of common stock upon exercise of warrants	18		18
Issuance of common stock upon exercise of warrants, Shares		2,039
Stock-based compensation	412		412
Foreign exchange translation adjustment	341			341
Unrealized gain (loss) on short-term investments	(24)			(24)
Net loss incurred	(26,848)				(26,848)
Ending balance at Mar. 31, 2018	93,704	$ 32	187,448	1,275	(95,051)
Ending balance, shares at Mar. 31, 2018		30,604,366
Beginning balances at Dec. 31, 2017	119,309	$ 32	186,522	958	(68,203)
Beginning balance, shares at Dec. 31, 2017		30,509,522
Foreign exchange translation adjustment	(515)
Unrealized gain (loss) on short-term investments	13
Net loss incurred	(38,442)
Ending balance at Jun. 30, 2018	82,709	$ 32	188,866	456	(106,645)
Ending balance, shares at Jun. 30, 2018		30,836,774
Beginning balances at Mar. 31, 2018	93,704	$ 32	187,448	1,275	(95,051)
Beginning balance, shares at Mar. 31, 2018		30,604,366
Issuance of common stock for settlement of RSUs, shares		13,125
Net Issuance of common stock upon cashless exercise of stock options, shares		87,099
Issuance of common stock upon exercise of stock options	30		30
Issuance of common stock upon exercise of stock options, shares		24,521
Issuance of common stock upon exercise of warrants	1		1
Issuance of common stock upon exercise of warrants, Shares		84
Common stock issued for purchase of assets	995		995
Common stock issued for purchase of assets, shares		107,579
Stock-based compensation	392		392
Foreign exchange translation adjustment	(856)			(856)
Unrealized gain (loss) on short-term investments	37			37
Net loss incurred	(11,594)				(11,594)
Ending balance at Jun. 30, 2018	82,709	$ 32	188,866	456	(106,645)
Ending balance, shares at Jun. 30, 2018		30,836,774
Beginning balances at Dec. 31, 2018	108,219	$ 36	237,702	200	(129,719)
Beginning balance, shares at Dec. 31, 2018		35,146,096
Issuance of common stock upon at the market offerings, net	4,890		4,890
Issuance of common stock upon at The market offering, net, shares		647,426
Issuance of common stock for settlement of RSUs, shares		13,125
Issuance of common stock upon exercise of stock options	6		6
Issuance of common stock upon exercise of stock options, shares		23,593
Stock-based compensation	1,000		1,000
Foreign exchange translation adjustment	(225)			(225)
Unrealized gain (loss) on short-term investments	26			26
Net loss incurred	(12,112)				(12,112)
Ending balance at Mar. 31, 2019	101,804	$ 36	243,598	1	(141,831)
Ending balance, shares at Mar. 31, 2019		35,830,240
Beginning balances at Dec. 31, 2018	108,219	$ 36	237,702	200	(129,719)
Beginning balance, shares at Dec. 31, 2018		35,146,096
Foreign exchange translation adjustment	(134)
Unrealized gain (loss) on short-term investments	146
Net loss incurred	(34,051)
Ending balance at Jun. 30, 2019	112,799	$ 40	276,317	212	(163,770)
Ending balance, shares at Jun. 30, 2019		38,903,830
Beginning balances at Mar. 31, 2019	101,804	$ 36	243,598	1	(141,831)
Beginning balance, shares at Mar. 31, 2019		35,830,240
Issuance of common stock upon at the market offerings, net	19,037	$ 2	19,035
Issuance of common stock upon at The market offering, net, shares		1,870,500
Issuance of common stock upon settlement of contingent liability	12,478	$ 1	12,477
Issuance of common stock upon settlement of contingent liability, shares		1,105,216
Issuance of common stock for settlement of RSUs, shares		13,125
Issuance of common stock upon cashless exercise of warrants, shares		11,119
Issuance of common stock upon exercise of stock options	61	$ 1	60
Issuance of common stock upon exercise of stock options, shares		73,630
Stock-based compensation	1,147		1,147
Foreign exchange translation adjustment	91			91
Unrealized gain (loss) on short-term investments	120			120
Net loss incurred	(21,939)				(21,939)
Ending balance at Jun. 30, 2019	$ 112,799	$ 40	$ 276,317	$ 212	$ (163,770)
Ending balance, shares at Jun. 30, 2019		38,903,830