Consolidated Condensed Statements of Comprehensive Income (Unaudited) (Parenthetical) (Less Than [Member], USD $) In Millions, unless otherwise specified	3 Months Ended
Aug. 31, 2013	Feb. 29, 2012
Less Than [Member]
Change in fair value of derivative, tax expense	$ 0	$ 0.1
Amortization of interest rate lock agreements, tax expense (benefit)	(0.1)	(0.1)
Change in fair value of available-for-sale securities, tax expense (benefit)	$ 0.1	$ 0.1

Amount of tax expense (benefit), after reclassification adjustments, of increase (decrease) in accumulated gain (loss) from derivative instruments designated and qualifying as the effective portion of cash flow hedges and an entity's share of an equity investee's increase (decrease) in deferred hedging gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 10A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=28358780&loc=SL7669646-108580

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 220

-SubTopic 10

-Section 45

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=28358780&loc=d3e640-108580

Name:	us-gaap_OtherComprehensiveIncomeLossDerivativesQualifyingAsHedgesTax
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration