OTHER FINANCIAL INFORMATION - Other Income (Expense), Net (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 28, 2018	Dec. 29, 2017
Other Financial Information [Abstract]
Gain on sale of privately-held company	$ 22.0	$ 0.0
Net foreign currency exchange gain	1.3	0.4
Net foreign currency exchange gain	(0.3)	(0.6)
Total other income (expense), net	$ 23.0	$ (0.2)