Remaining Annual Purchase Requirements under Contract (Detail) € in Millions	Sep. 30, 2018 EUR (€)
Remaining Annual Purchase Requirements under Contract
2018	€ 4.4
2019	11.6
2020	15.5
2021	15.5
2022	19.4
2023	€ 19.4

Minimum amount of purchase arrangement maturing in the fourth 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_PurchaseObligationDueInFourthYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant