Commitments and Contingencies - Letters of Credit (Details) $ in Millions	Mar. 31, 2016 USD ($)
Commitments and Contingencies Disclosure [Line Items]
Surety bonds issued	$ 161
Outside Effective Credit Facility
Commitments and Contingencies Disclosure [Line Items]
Letters of credit outstanding	$ 77

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