Guarantees (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended	9 Months Ended
Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Guarantor Obligations [Line Items]
Contingent liability for standby letters of credit, issued and outstanding	$ 7.8		$ 7.8
Advanced Filtration Systems, Inc. [Member]
Guarantor Obligations [Line Items]
Outstanding debt of joint venture	29.0		29.0
Joint venture investment earnings	0.9	0.7	2.2	1.4
Royalty income	$ 1.7	$ 1.4	$ 5.0	$ 4.4

Amount of long-term debt before deduction of unamortized discount or premium. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, with initial maturities beyond one year or the normal operating cycle, if longer.

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20

-Article 5

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 22

-Article 5

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

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

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant