The cash outflow to reacquire common stock during the period.

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 20

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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

-Glossary Financing Activities

-URI http://asc.fasb.org/extlink&oid=6513228

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

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 95

-Paragraph 18

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 15

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3291-108585

Name:	us-gaap_PaymentsForRepurchaseOfCommonStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

Stockholders' Equity - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		0 Months Ended		3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Sep. 07, 2012 Class A nonvoting common stock [Member]	Sep. 12, 2011 Class A nonvoting common stock [Member]	Apr. 30, 2013 Class A nonvoting common stock [Member]	Oct. 31, 2012 Class A nonvoting common stock [Member]	Apr. 30, 2013 Class A nonvoting common stock [Member]	Jul. 31, 2012 Class A nonvoting common stock [Member]
Schedule Of Stockholders Equity [Line Items]
Shares authorized for repurchase			2,000,000	2,000,000
Shares remaining for repurchase								334,940
Number of shares reacquired					0		188,167
Value of reacquired shares in connection with its repurchase plan	$ 5,121	$ 12,309				$ 5,121	$ 5,121