Debt and Credit Facilities Credit Facilities (Details)	Apr. 30, 2016 USD ($)
Eight Hundred Million Credit Facility Expiring November 2018 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 800,000,000
Line of Credit Facility, Covenant Compliance, Ratio of Earnings Before Interest, Taxes, Deprecation, and Amortization to Consolidated Interest Expense	3
Four Hundred Million Credit Facility Expiring May 2017 [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Current Borrowing Capacity	$ 400,000,000