Summary of Share Based Compensation Expense Related to Share Based Payment Awards and Employee Stock Purchases (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Mar. 27, 2015	Mar. 28, 2014	Mar. 27, 2015	Mar. 28, 2014
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	$ 790	$ 374	$ 1,734	$ 788
Cost of sales
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	66	21	143	46
Research and development, net
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	67	10	89	19
Sales and marketing
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	161	49	352	86
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	496	294	1,150	637
Operating expense
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Share based compensation expense related to employee stock options, restricted stock awards and employee stock purchase plan	$ 724	$ 353	$ 1,591	$ 742