Derivatives and Financial Instruments - Assets and Liabilities Measured at Fair Value Additional Information (Detail) $ in Millions	3 Months Ended
Dec. 31, 2017 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carrying value of intangible assets after impairment	$ 10.8

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

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