Fair Value Measurement (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Dec. 31, 2016
Assets:
Marketable securities	$ 64,255	$ 61,868
Foreign exchange contracts	42	6
Government bonds
Assets:
Marketable securities	494	497
Corporate bonds
Assets:
Marketable securities	63,761	61,371
Level II
Assets:
Foreign exchange contracts	42	6
Level II | Government bonds
Assets:
Marketable securities	494	497
Level II | Corporate bonds
Assets:
Marketable securities	$ 63,761	$ 61,371