Option Activity and Changes (Detail)	6 Months Ended
	Jul. 01, 2017 $ / shares shares
Shares
Options outstanding at December 31, 2016 | shares	2,740,364
Options granted | shares	383,825
Options cancelled and forfeited | shares	(39,604)
Options exercised | shares	(101,954)
Options outstanding at July 1, 2017 | shares	2,982,631
Options exercisable at July 1, 2017 | shares	2,109,908
Weighted Average Exercise Price
Options outstanding at December 31, 2016 | $ / shares	$ 7.00
Options granted | $ / shares	12.42
Options cancelled and forfeited | $ / shares	11.82
Options exercised | $ / shares	7.03
Options outstanding at July 1, 2017 | $ / shares	7.63
Options exercisable at July 1, 2017 | $ / shares	$ 7.22