Common Shares (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Apr. 30, 2014	Jul. 31, 2014
Common Shares Information
Common shares authorized	300,000,000	300,000,000
Common shares outstanding	101,697,400	101,816,841
Treasury shares	26,907,765	26,788,324
Common Shares (Additional Textual) [Abstract]
Shares repurchased during period	4,900,000
Purchase amount for shares repurchased	$ 495.0
Shares remaining for repurchase		5,000,000