Restructuring and Related Costs Restructuring and Related Costs (Restructuring Reserve Rollforward) (Details) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Mar. 30, 2019	Mar. 31, 2018
2018 Restructuring Plan
Restructuring Reserve [Roll Forward]
Restructuring expense	$ 0	$ 0	$ 0	$ 0
Test & Simulation
Restructuring Reserve [Roll Forward]
Restructuring expense	0	$ 346,000	130,000	$ 601,000
Test & Simulation | 2018 Restructuring Plan
Restructuring Reserve [Roll Forward]
Balance, September 29, 2018			1,051,000
Restructuring expense			0
Payments			(1,012,000)
Other adjustments			(39,000)
Currency translation			0
Balance, March 30, 2019	0		0
Test & Simulation | 2017 Restructuring Plan
Restructuring Reserve [Roll Forward]
Balance, September 29, 2018			2,933,000
Restructuring expense			130,000
Payments			(3,058,000)
Other adjustments			(5,000)
Currency translation			0
Balance, March 30, 2019	$ 0		$ 0