GOODWILL AND INTANGIBLE ASSETS (Net intangible assets) (Details) - USD ($) $ in Thousands	12 Months Ended
	Sep. 28, 2019	Sep. 29, 2018
Finite-Lived Intangible Assets [Line Items]
Net intangible assets	$ 42,651	$ 52,871
Developed technology [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	87,209	90,500
Accumulated amortization	(48,718)	(45,229)
Net intangible assets	38,491	45,271
Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	35,180	36,131
Accumulated amortization	(31,862)	(29,820)
Net intangible assets	3,318	6,311
Trade name [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	7,219	7,377
Accumulated amortization	(6,377)	(6,088)
Net intangible assets	842	1,289
Other intangible assets [Member]
Finite-Lived Intangible Assets [Line Items]
Gross intangible assets	2,500	2,500
Accumulated amortization	(2,500)	(2,500)
Net intangible assets	$ 0	$ 0
Average estimated useful lives (in years)	1 year 10 months 24 days
Minimum [Member] | Developed technology [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	7 years
Minimum [Member] | Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	5 years
Minimum [Member] | Trade name [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	7 years
Maximum [Member] | Developed technology [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	15 years
Maximum [Member] | Customer relationships [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	6 years
Maximum [Member] | Trade name [Member]
Finite-Lived Intangible Assets [Line Items]
Average estimated useful lives (in years)	8 years