Summary of Significant Accounting Policies (Details 5) (USD $) In Millions, unless otherwise specified	12 Months Ended
	May 31, 2014
Future rent due to us under non-cancelable leases
2015	$ 19.9
2016	20.4
2017	19.9
2018	19.3
2019	$ 18.6
Minimum
Equipment under leases
Period of short-term leases	1 month
Period of long-term lease	12 months
Maximum
Equipment under leases
Period of short-term leases	12 months