Borrowings (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Aug. 31, 2012
Borrowings (Additional Textual) [Abstract]
Interest rate provisions in the loan agreement	Reference rate minus 0.25% or LIBOR plus 1.50%
Margin on loans bears interest at the reference rate minus	0.25%
Margin on loans bears interest at the LIBOR plus	1.50%
Maximum [Member]
Borrowings (Textual) [Abstract]
Maturity date of Commercial Credit Agreement	Oct. 01, 2015
Commercial Credit Agreement [Member]
Borrowings (Textual) [Abstract]
Maximum aggregate outstanding principal amount under Commercial Credit Agreement	25,000

Description of the interest rate for the amounts borrowed under the credit facility, including the terms and the method for determining the interest rate (for example, fixed or variable, LIBOR plus a percentage, increasing rate, timing of interest rate resets, remarketing provisions).

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration