Summary of Significant Accounting Policies - Additional Information (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended			9 Months Ended	12 Months Ended
	Mar. 08, 2018	Mar. 31, 2019	Mar. 31, 2019	Sep. 30, 2018	Jun. 30, 2018	Sep. 30, 2019	Dec. 31, 2018
Significant Accounting Policies [Line Items]
Operating lease, ROU asset		$ 2,400	$ 2,400			$ 2,112
Operating lease liability		2,900	$ 2,900			2,528
Removal of deferred rent						$ 600
Recognition of beneficial conversion feature SafeOp convertible notes		$ 200
SafeOp Surgical, Inc. | Common Stock
Significant Accounting Policies [Line Items]
Stock issued for acquisition	2,975,209		886,843	174,302	115,621	886,843	443,421
Fair value, inputs, level 3
Significant Accounting Policies [Line Items]
Vesting period						4 years
Fair value of the cash settled award						$ 1,100