Commitments and Contingencies (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
May 31, 2013	May 31, 2012
Amounts of obligations from repurchased units and incurred net losses for the periods
Number of units repurchased	$ 3
Obligations from units repurchased	31
Net losses on repurchased units

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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