Components of Accumulated Other Comprehensive Loss (Parenthetical) (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016	Jun. 30, 2016	Dec. 31, 2015
Unrealized Net Gains (Losses) on Available for Sale Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Unrealized net gains (losses), taxes (benefits)	$ 59	$ 61
Foreign Exchange Contract [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Unrealized net gains (losses), taxes (benefits)	$ 801	$ 402	$ 251	$ 166