Supplemental Disclosure of Cash Flow Information (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 28, 2012	Sep. 30, 2011	Sep. 28, 2012	Sep. 30, 2011
Cash paid during period:
Income taxes			$ 16,026	$ 14,147
Non-cash investing and financing activities:
Unrealized (loss) gain on short-term investments	(17)	23	(5)	50
Vested stock unit awards issued to settle accrued bonuses			5,343	4,538
Stock repurchases payable to broker				$ 782