Commitments (Additional Information) (Detail) $ in Millions	Mar. 31, 2017 USD ($)
Standby Letters of Credit
Other Commitments And Contingencies [Line Items]
Amount outstanding	$ 79
Performance Guarantee
Other Commitments And Contingencies [Line Items]
Surety bonds	$ 131

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

No definition available.

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