Derivative Instruments and Hedging Activities (Details) (USD $) In Millions, unless otherwise specified	Aug. 31, 2013	May 31, 2013
Derivative Instruments and Hedging Activities
Number of derivative financial instruments	2
Interest rate cap \| Derivatives designated as hedging instruments:
Fair value carrying amount of the Company's interest rate derivatives
Derivative Assets	$ 0.2	$ 0.1
Interest rate cap \| Derivatives designated as hedging instruments: \| Cash flow hedges
Derivative Instruments and Hedging Activities
Notional amount under revolving credit agreement	50.0
Interest rate swap \| Derivatives designated as hedging instruments:
Fair value carrying amount of the Company's interest rate derivatives
Derivative Liabilities	(2.4)	(3.6)
Interest rate swap \| Derivatives designated as hedging instruments: \| Cash flow hedges
Derivative Instruments and Hedging Activities
Notional amount under revolving credit agreement	$ 50.0

Fair value of all asset derivatives designated as cash flow hedging instruments.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 4B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5624163-113959

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- Definition

Fair value of all liability derivatives designated as cash flow hedging instruments.

+ References

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- Definition

Nominal or face amount used to calculate payments on the derivative liability.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1B

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5580258-113959

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 815

-SubTopic 10

-Section 50

-Paragraph 1A

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=7476318&loc=SL5579245-113959

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Notional Amount

-URI http://asc.fasb.org/extlink&oid=6519104

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- Definition

The number of derivative instruments of a particular group held by the entity.

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