Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Treasury Stock	Additional Paid-in Capital	Accumulated Deficit	Accumulated Other Comprehensive (Loss) Income
Balance (in shares) at Dec. 31, 2017		15,329	0
Balance at Dec. 31, 2017	$ 178,850	$ 16	$ 0	$ 621,446	$ (447,640)	$ 5,028
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	9,039			9,039
Issuance of common stock and warrants, net of issuance costs	279			279
Issuance of common stock for MST acquisition (in Shares)		242
Issuance of common stock for MST Acquisition	8,300	$ 0		8,300
Exercise of stock options and warrants (in Shares)		889
Exercise of stock options and warrants	36,172	$ 1		36,171
Award of restricted stock units (in Shares)		82
Award of restricted stock units	0	$ 0
Return of common stock to pay withholding taxes on restricted stock (in Shares)			(41)
Return of common stock to pay withholding taxes on restricted stock	(1,662)		$ 1	(1,663)
Cancellation of treasury stock (in Shares)			(41)
Cancellation of treasury stock	(1)		$ (1)
Issuance of common stock related to sale of SurgiBot assets, Shares		100
Issuance of common stock related to sale of SurgiBot assets	3,000	$ 0		3,000
Cumulative effect of change in accounting principle (Note 2)	11				11
Other comprehensive loss	(3,690)					(3,690)
Net loss	(61,777)				(61,777)
Balance (in shares) at Dec. 31, 2018		16,642	0
Balance at Dec. 31, 2018	168,521	$ 17	$ 0	676,572	(509,406)	1,338
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stock-based compensation	11,508			11,508
Issuance of common stock, net of issuance costs (in shares)		3,571
Issuance of common stock, net of issuance costs	25,777	$ 4		25,773
Issuance of common stock for MST acquisition (in Shares)		370
Issuance of common stock for MST Acquisition	6,599	$ 0		6,599
Exercise of stock options and warrants (in Shares)		38
Exercise of stock options and warrants	538	$ 0		538
Award of restricted stock units (in Shares)		70
Award of restricted stock units	0	$ 0
Return of common stock to pay withholding taxes on restricted stock (in Shares)			(15)
Return of common stock to pay withholding taxes on restricted stock	(499)		$ 0	(499)
Cancellation of treasury stock (in Shares)			(15)
Cancellation of treasury stock	0
Cumulative effect of change in accounting principle (Note 2)	0			(7)	7
Other comprehensive loss	(2,708)					(2,708)
Net loss	(154,201)				(154,201)
Balance (in shares) at Dec. 31, 2019		20,691	0
Balance at Dec. 31, 2019	$ 55,535	$ 21	$ 0	$ 720,484	$ (663,600)	$ (1,370)