Commitments and Contingencies (Letters of Credit) (Narrative) (Details) $ in Millions	Jan. 31, 2016 USD ($)
Other Liabilities, Unclassified [Abstract]
Letters of Credit Outstanding, Amount	$ 422

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