Fair Value Measurements (Details) - USD ($) $ in Thousands	3 Months Ended
	Dec. 30, 2017	Dec. 31, 2016	Dec. 30, 2017	Sep. 30, 2017
Financial assets:
Cash equivalents			$ 74,705	$ 49,845
Marketable securities			50,567	50,315
Forward contracts			2,694	1,163
Financial assets, fair value			127,966	101,323
Financial liabilities:
Contingent consideration related to acquisitions	$ 8,400		4,643	8,400
Forward contracts			4,333	4,347
Liabilities, Fair Value Disclosure, Recurring			8,976	12,747
Business Combination. Contingent Consideration [Roll Forward]
Beginning balance	8,400
Payment of contingent consideration	(3,800)	$ (3,100)
Ending balance	4,643
Level 1
Financial assets:
Cash equivalents			74,705	49,845
Financial assets, fair value			122,662	97,518
Level 2
Financial assets:
Forward contracts			2,694	1,163
Financial assets, fair value			5,304	3,805
Financial liabilities:
Forward contracts			4,333	4,347
Liabilities, Fair Value Disclosure, Recurring			4,333	4,347
Level 3
Financial liabilities:
Contingent consideration related to acquisitions	8,400	19,570	4,643	8,400
Liabilities, Fair Value Disclosure, Recurring			4,643	8,400
Business Combination. Contingent Consideration [Roll Forward]
Beginning balance	8,400	19,570
Change in present value of contingent consideration		74
Payment of contingent consideration		(3,050)
Ending balance	4,643	16,594
ColdLight | Level 3
Financial liabilities:
Contingent consideration related to acquisitions		2,500
Business Combination. Contingent Consideration [Roll Forward]
Beginning balance		2,500
Change in present value of contingent consideration		0
Payment of contingent consideration		(1,250)
Ending balance		1,250
Kepware | Level 3
Financial liabilities:
Contingent consideration related to acquisitions	8,400	17,070	4,643	8,400
Business Combination. Contingent Consideration [Roll Forward]
Beginning balance	8,400	17,070
Change in present value of contingent consideration		74
Payment of contingent consideration	(3,757)	(1,800)
Ending balance	$ 4,643	$ 15,344
Certificates of deposit
Financial assets:
Marketable securities			220	240
Certificates of deposit | Level 2
Financial assets:
Marketable securities			220	240
Corporate notes/bonds
Financial assets:
Marketable securities			47,957	47,673
Corporate notes/bonds | Level 1
Financial assets:
Marketable securities			47,957	47,673
U.S. government agency securities
Financial assets:
Marketable securities			2,390	2,402
U.S. government agency securities | Level 2
Financial assets:
Marketable securities			$ 2,390	$ 2,402