Termination and Settlement of Elite Medical Holdings and Pac 3 Surgical Collaboration Agreement - Additional Information (Details) - Collaborative Arrangement - Elite Medical Holdings and Pac 3 Surgical - USD ($) $ in Millions	1 Months Ended	6 Months Ended
	Feb. 28, 2018	Jun. 30, 2018
Termination And Settlement Of Collaboration Agreement [Line Items]
Payments of settlement	$ 0.4
Gain on contract termination and settlement		$ 6.2