Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive (Loss) Income [Member]
Balance at Dec. 31, 2017	$ 178,848	$ 199		$ 621,261	$ (447,640)	$ 5,028
Balance, Shares at Dec. 31, 2017		199,282
Stock-based compensation	1,834			1,834
Issuance of common stock and warrants, net of issuance costs	11			11
Exercise of stock options and warrants	2,228	$ 1		2,227
Exercise of stock options and warrants, Shares		1,038
Award of restricted stock units, Shares		367
Return of common stock to pay withholding taxes on restricted stock			$ 174
Cancellation of treasury stock			(174)
Issuance of common stock related to sale of SurgiBot assets	3,000	$ 1		2,999
Issuance of common stock related to sale of SurgiBot assets, Shares		1,286
Cumulative effect of change in accounting principle	11				11
Other comprehensive (loss) income	2,308					2,308
Net loss	(882)				(882)
Balance at Mar. 31, 2018	187,358	$ 201		628,332	(448,511)	7,336
Balance, Shares at Mar. 31, 2018		201,973
Balance at Dec. 31, 2018	168,521	$ 216		676,373	(509,406)	1,338
Balance, Shares at Dec. 31, 2018		216,346
Stock-based compensation	2,981			2,981
Exercise of stock options and warrants	236			236
Exercise of stock options and warrants, Shares		159
Award of restricted stock units	1	$ 1
Award of restricted stock units, Shares		613
Return of common stock to pay withholding taxes on restricted stock	(499)		$ 194	(499)
Cancellation of treasury stock			(194)
Cumulative effect of change in accounting principle				(7)	7
Other comprehensive (loss) income	(1,949)					(1,949)
Net loss	(22,525)				(22,525)
Balance at Mar. 31, 2019	$ 146,766	$ 217		$ 679,084	$ (531,924)	$ (611)
Balance, Shares at Mar. 31, 2019		217,118