This item represents the gross unrealized gains for securities, at a point in time, which are categorized neither as held-to-maturity nor trading securities.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 133

-Paragraph 22

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 320

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=6872113&loc=d3e27161-111563

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 115

-Paragraph 13, 19

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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.

Name:	us-gaap_AvailableforsaleSecuritiesGrossUnrealizedGain
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Marketable Securities (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2013	Jul. 31, 2012
Summary of marketable securities
Amortized Cost	$ 10,830
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	10,830
Certificates of deposit [Member]
Summary of marketable securities
Amortized Cost	6,247
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	6,247
Federal Farm Credit Bank debt security [Member]
Summary of marketable securities
Amortized Cost	260
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	260
Municipal bonds [Member]
Summary of marketable securities
Amortized Cost	4,323
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	$ 4,323