Restructuring and Related Costs (Restructuring Reserve Rollforward) (Details) - Test & Simulation - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Mar. 28, 2020	Mar. 28, 2020
Restructuring Reserve [Roll Forward]
Balance, September 28, 2019		$ 0
Restructuring expense	$ 6,138	6,138
Balance, March 28, 2020	$ 6,138	$ 6,138

Amount of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration