Accrued Liabilities - Accrued Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables and Accruals [Abstract]
Employee compensation	$ 8,240	$ 8,039
Royalties payable	896	828
Accounting and legal	567	427
Sales, use and other taxes	420	551
Clinical study costs	370	563
Warranty reserves	304	299
Other accrued liabilities	1,547	1,474
Total accrued liabilities	$ 12,344	$ 12,181