Income (Loss) Per Share - Numerators and Denominators of Basic and Diluted Net Income (Loss) Per Share Computations (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016
Numerator:
Net loss	$ (15,583)	$ (16,012)	$ (71,110)	$ (61,871)
Denominator:
Basic and diluted	81,445	78,092	80,618	77,475
Net loss per share:
Basic and diluted	$ (0.19)	$ (0.21)	$ (0.88)	$ (0.80)