Quarterly Results of Operation (Unaudited) - Summary of Unaudited Quarterly Results of Operations (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Total revenues	$ 7,524	$ 5,422	$ 6,389	$ 4,767	$ 3,398	$ 183	$ 1,584	$ 1,946	$ 24,102	$ 7,111
Cost of revenue	5,635	4,249	3,732	2,555	3,500	921	972	1,334	16,171	6,727
Gross profit	1,889	1,173	2,657	2,212	(102)	(738)	612	612	7,931	384	$ 450
Amortization of intangible assets	2,624	2,674	2,743	2,827	2,714	1,821	1,687	1,636	10,868	7,858	6,967
Change in fair value of contingent consideration	(1,092)	(1,358)	812	627	800	773	(774)	1,227	(1,011)	2,026	482
Acquisition related costs	302	345							647
Gain from sale of SurgiBot assets, net	75	44	37	(11,996)					(11,840)
Issuance costs for warrants							627			627
Other operating expenses	18,205	14,343	14,954	13,911	14,298	12,337	11,538	13,627	61,413	51,800
Change in fair value of warrant liabilities	(10,118)	8,760	17,507	(1,829)	58,521	22,887	2,326		14,320	83,734
Reversal of transfer fee accrual		(2,994)							(2,994)
Interest income, interest expense and other expense	(843)	346	1,735	444	684	695	662	394	1,682	2,435
Loss before income taxes	(7,264)	(20,987)	(35,131)	(1,772)	(77,119)	(39,251)	(15,454)	(16,272)	(65,154)	(148,096)	(125,503)
Income tax benefit	823	781	883	890	963	738	741	858	3,377	3,300	5,523
Net loss	$ (6,441)	$ (20,206)	$ (34,248)	$ (882)	$ (76,156)	$ (38,513)	$ (14,713)	$ (15,414)	$ (61,777)	$ (144,796)	$ (119,980)
Net loss per share - basic and diluted	$ (0.03)	$ (0.10)	$ (0.17)	$ 0.00	$ (0.40)	$ (0.26)	$ (0.11)	$ (0.13)	$ (0.30)	$ (0.97)	$ (1.07)