Supplemental Disclosure of Cash Flow Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017
Cash paid during period:
Income taxes	$ 678	$ 446
Non-cash investing and financing activities:
Unrealized (loss) gain on short-term investments	(40)	36
Vested stock unit awards issued to settle accrued bonuses	7,643	6,910
Accrual for capital expenditures	$ 299	$ 405