Restructuring and Related Costs (Summary of Restructuring Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2018	Jul. 01, 2017	Jun. 30, 2018	Jul. 01, 2017
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 735	$ 92	$ 1,343	$ 1,036
Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	739	0	1,340	0
Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(4)	92	3	1,036
Cost of sales
Restructuring Cost and Reserve [Line Items]
Restructuring charges	386	67	810	647
Cost of sales | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	386	0	810	0
Cost of sales | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	67	0	647
Selling and marketing
Restructuring Cost and Reserve [Line Items]
Restructuring charges	154	10	161	136
Selling and marketing | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	158	0	158	0
Selling and marketing | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	(4)	10	3	136
General and administrative
Restructuring Cost and Reserve [Line Items]
Restructuring charges	52	15	229	253
General and administrative | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	52	0	229	0
General and administrative | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	0	15	0	253
Research and development
Restructuring Cost and Reserve [Line Items]
Restructuring charges	143	0	143	0
Research and development | Test
Restructuring Cost and Reserve [Line Items]
Restructuring charges	143	0	143	0
Research and development | Sensors
Restructuring Cost and Reserve [Line Items]
Restructuring charges	$ 0	$ 0	$ 0	$ 0