FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Jun. 28, 2019	Sep. 28, 2018
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	$ 57.5	$ 62.5
Fair Value, Measurements, Recurring
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	74.2	106.6
Derivative liabilities	(0.3)
Contingent consideration	(38.2)	(24.4)
Total liabilities measured at fair value	(38.5)	(24.4)
Fair Value, Measurements, Recurring \| MPTC Series B-1 Bonds
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	26.6	25.1
Fair Value, Measurements, Recurring \| MPTC Series B-2 Bonds (1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	24.5	23.1
Fair Value, Measurements, Recurring \| APTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	6.4	6.4
Fair Value, Measurements, Recurring \| GPTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities		7.9
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Instruments
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	16.7	44.1
Derivative liabilities	0.0
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
Assets/Liabilities Measured at Fair Value on a Recurring Basis
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 (1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Instruments \| APTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Instruments \| GPTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities		0.0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	57.5	62.5
Derivative liabilities	(0.3)
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	(0.3)	0.0
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs \| MPTC Series B-1 Bonds
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	26.6	25.1
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs \| MPTC Series B-2 Bonds (1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	24.5	23.1
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs \| APTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	6.4	6.4
Fair Value, Measurements, Recurring \| Significant Other Observable Inputs \| GPTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities		7.9
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	0.0	0.0
Derivative liabilities	0.0
Contingent consideration	(38.2)	(24.4)
Total liabilities measured at fair value	(38.2)	(24.4)
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs \| MPTC Series B-1 Bonds
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs \| MPTC Series B-2 Bonds (1)
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs \| APTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities	0.0	0.0
Fair Value, Measurements, Recurring \| Significant Unobservable Inputs \| GPTC Securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Available-for-sale securities		0.0
Money Market Funds \| Fair Value, Measurements, Recurring
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents	16.7	44.1
Money Market Funds \| Fair Value, Measurements, Recurring \| Quoted Prices in Active Markets for Identical Instruments
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents	16.7	44.1
Money Market Funds \| Fair Value, Measurements, Recurring \| Significant Other Observable Inputs
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents	0.0	0.0
Money Market Funds \| Fair Value, Measurements, Recurring \| Significant Unobservable Inputs
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Cash equivalents	$ 0.0	$ 0.0

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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Amount of short-term, highly liquid investments that are both readily convertible to known amounts of cash and so near their maturity that they present insignificant risk of changes in value because of changes in interest rates. Excludes cash and cash equivalents within disposal group and discontinued operation.

+ References

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Fair value, after the effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and not elected to be offset.

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Fair value of financial and nonfinancial obligations.

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Contingent Consideration Liability, Fair Value

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