Summary of Significant Accounting Policies Foreign Currency Hedging (Details)	12 Months Ended
Jul. 31, 2017
Derivative Instruments and Hedging Activities Disclosure [Abstract]
Derivative maturity	18 months

Period remaining until the derivative contract matures, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

No definition available.

Name:	us-gaap_DerivativeRemainingMaturity1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration