Fair Value Measurements (Narrative) (Details) - USD ($) $ in Thousands	6 Months Ended
	Mar. 30, 2019	Mar. 31, 2018	Sep. 30, 2018	Sep. 30, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions	$ 0		$ 1,575
Payment of contingent consideration	1,600	$ 3,800
Business Combination, Consideration Transferred, Liabilities Incurred	1,600	3,200
Cost Method Investments	9,400		1,700
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions	$ 0	6,743	$ 1,575	$ 8,400
Payment of contingent consideration		3,757
Level 3 | Accrued Expenses and Other Current Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions		5,700
Level 3 | Other Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions		1,100
Kepware | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent consideration related to acquisitions		4,643		$ 8,400
Payment of contingent consideration		$ 3,757