FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Details) - USD ($) $ in Millions	Apr. 03, 2020	Sep. 27, 2019
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	$ 60.4	$ 58.8
Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	3.4	2.8
Total assets measured at fair value	163.8	61.8
Contingent consideration	(75.0)	(75.3)
Total liabilities measured at fair value	(75.0)	(75.3)
Fair Value, Measurements, Recurring | MPTC Series B-1 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	28.1	27.1
Fair Value, Measurements, Recurring | MPTC Series B-2 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	26.2	25.1
Fair Value, Measurements, Recurring | APTC securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	6.1	6.6
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	0.0	0.0
Total assets measured at fair value	100.0	0.2
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments | MPTC Series B-1 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments | MPTC Series B-2 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments | APTC securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	3.4	2.8
Total assets measured at fair value	63.8	61.6
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs | MPTC Series B-1 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	28.1	27.1
Fair Value, Measurements, Recurring | Significant Other Observable Inputs | MPTC Series B-2 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	26.2	25.1
Fair Value, Measurements, Recurring | Significant Other Observable Inputs | APTC securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	6.1	6.6
Fair Value, Measurements, Recurring | Significant Unobservable Inputs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Derivative assets	0.0	0.0
Total assets measured at fair value	0.0	0.0
Contingent consideration	(75.0)	(75.3)
Total liabilities measured at fair value	(75.0)	(75.3)
Fair Value, Measurements, Recurring | Significant Unobservable Inputs | MPTC Series B-1 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs | MPTC Series B-2 Bonds
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs | APTC securities
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Available-for-sale securities	0.0	0.0
Money market funds | Fair Value, Measurements, Recurring
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	100.0	0.2
Money market funds | Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Instruments
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	100.0	0.2
Money market funds | Fair Value, Measurements, Recurring | Significant Other Observable Inputs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	0.0	0.0
Money market funds | Fair Value, Measurements, Recurring | Significant Unobservable Inputs
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Cash equivalents	$ 0.0	$ 0.0