Restructuring and Related Costs (Summary of Restructuring Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 246	$ 563
Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	255	0
Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(9)	563
Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	120	326
Cost of sales | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	120	0
Cost of sales | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	326
Selling and marketing
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(9)	81
Selling and marketing | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
Selling and marketing | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(9)	81
General and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring charges	135	156
General and administrative | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	135	0
General and administrative | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	156
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
Research and development | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	0
Research and development | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 0