Consolidated Statements of Shareholders' Equity - 3 months ended Mar. 31, 2018 - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Deficit [Member]	Accumulated Other Comprehensive 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		367
Return of common stock to pay withholding taxes on restricted stock, Shares			174
Cancellation of treasury stock, Shares			(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 (Note 2)	11				11
Other comprehensive 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