Guarantees (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Oct. 31, 2011	Oct. 31, 2010
Guarantees [Abstract]
Outstanding debt of joint venture	$ 12.2
Equity method investment, earnings	0.7	0.2
Royalty income	1.7	1.7
Total contingent liability for standby letters of credit, issued and outstanding	11.4
Amount drawn upon letters of credit	$ 0