Other Current Liabilities - Summary of Other Current Liabilities (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Payables And Accruals [Abstract]
Accrued expenses	$ 6,984	$ 6,155
Salaries, bonuses, commissions and related taxes payable	24,635	19,636
Accrued distributor commissions	9,192	9,379
Accrued legal and settlement expenses	7,673	23,081
Non-income taxes payable	3,180	7,301
Other payables	9,631	3,536
Other current liabilities	$ 61,295	$ 69,088