Segment and Geographic Information and Significant Customers - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Nov. 07, 2018
Segment Reporting [Abstract]
Disposal Group, Including Discontinued Operation, Consideration			$ 400.0
Stranded Costs	$ 7.0	$ 7.8

Amount of consideration received or receivable for the disposal of assets and liabilities, including discontinued operation.

No definition available.

Name:	us-gaap_DisposalGroupIncludingDiscontinuedOperationConsideration
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant