SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (New Accounting Pronouncements) (Narrative) (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 29, 2017	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017	Sep. 28, 2019
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents		$ 172,382	$ 121,877
Reduction of operating expenses		(185,982)	(178,839)	$ (165,349)
Write off of currency translation amounts		796	$ 4,122	$ 3,060
Accounting Standards Update 2017-07
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Reduction of operating expenses	$ 848
Write off of currency translation amounts	$ 848
Foreign
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Cash and cash equivalents		$ 41,110
Subsequent Event | Accounting Standards Update 2016-02
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Operating lease assets					$ 40,000
Operating lease liabilities					$ 45,000