Income Taxes - Additional Information (Detail) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Valuation allowance	$ (2,624)	$ (4,440)
Unrecognized tax benefit	12,683	5,711	$ 3,658	$ 3,497
Unrecognized Tax Benefits that Would Impact Effective Tax Rate	8,900
Federal
Income Taxes [Line Items]
Operating Loss Carryforwards	3,000	4,000
Foreign Tax Authority
Income Taxes [Line Items]
Operating Loss Carryforwards	11,000	16,000
Unrecognized Tax Benefits Before Interest And Penalties
Income Taxes [Line Items]
Unrecognized tax benefit	$ 11,505	$ 5,269	$ 3,357	$ 3,397