Comprehensive Income (Loss) - Additional Information (Detail) $ in Millions	6 Months Ended
Mar. 31, 2019 USD ($)
Maximum
Accumulated Other Comprehensive Income Loss [Line Items]
Changes in accumulated other comprehensive loss, net of related taxes	$ 1

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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