FAIR VALUE - Assets and Liabilities Measured at Fair Value on Recurring Basis (Detail) - USD ($) $ in Millions	Mar. 31, 2017	Sep. 30, 2016
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Fair Value	$ 60.5	$ 95.3
Fair Value, Measurements, Recurring
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	60.5	95.3
Contingent consideration	(1.1)	(1.3)
Total liabilities measured at fair value	(1.1)	(1.3)
Fair Value, Measurements, Recurring | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Fair Value	60.5	95.3
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	0.0	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 | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Fair Value	0.0	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	0.0	0.0
Contingent consideration	0.0	0.0
Total liabilities measured at fair value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Fair Value	0.0	0.0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Total assets measured at fair value	60.5	95.3
Contingent consideration	(1.1)	(1.3)
Total liabilities measured at fair value	(1.1)	(1.3)
Fair Value, Measurements, Recurring | Significant Unobservable Inputs | Corporate debt securities
Assets/Liabilities Measured at Fair Value on a Recurring Basis
Fair Value	$ 60.5	$ 95.3