Commitments and Contingencies - Additional Information (Detail) $ in Millions	Sep. 30, 2018 USD ($)
Purchase Commitment, Excluding Long-term Commitment
Aggregate purchase commitments	$ 275.6
Purchase commitments less than one year	$ 263.3

Minimum amount of purchase arrangement maturing in the next fiscal year following the latest fiscal year. Includes, but not limited to, recorded and unrecorded purchase obligations, long-term purchase commitments, and short-term purchase commitments.

No definition available.

Name:	us-gaap_PurchaseObligationDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant