Line of credit facility expiration period

Name:	dci_LineOfCreditFacilityExpirationPeriod
Namespace Prefix:	dci
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of Uncommitted Credit Facilities

+ Details

Name:	dci_NumberOfUncommittedCreditFacilities
Namespace Prefix:	dci
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

+ Details

Name:	us-gaap_LineOfCreditFacilityAmountOutstanding
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects when the credit facility terminates, which may be presented in a variety of ways (year, month and year, day, month and year, quarter).

+ References

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-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009.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 SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 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 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityExpirationDate
Namespace Prefix:	us-gaap
Data Type:	us-types:dateStringItemType
Balance Type:	na
Period Type:	duration

- Definition

The effective interest rate at the end of the reporting period.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19, 22
-Article 5

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

+ Details

Name:	us-gaap_LineOfCreditFacilityInterestRateAtPeriodEnd
Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

Name:	us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of short-term debt outstanding by type or by instrument at that time.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Section 02
-Paragraph 19
-Subparagraph b
-Article 5

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

+ Details

Name:	us-gaap_ShortTermDebtWeightedAverageInterestRate
Namespace Prefix:	us-gaap
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Credit Facilities (Details) In Millions, unless otherwise specified	12 Months Ended						12 Months Ended
	Jul. 31, 2011 USD ($)	Jul. 31, 2010 USD ($)	Jul. 31, 2011 European Operations [Member] EUR (€)	Jul. 31, 2010 European Operations [Member] EUR (€)	Jul. 31, 2011 European Operations [Member] Treasury Notes Program [Member] EUR (€)	Jul. 31, 2010 European Operations [Member] Treasury Notes Program [Member] EUR (€)	Jul. 31, 2011 Multi-Currency Revolving Facility [Member] USD ($)	Jul. 31, 2010 Multi-Currency Revolving Facility [Member] USD ($)	Jul. 31, 2011 Uncommitted Credit Facilities [Member] USD ($)	Jul. 31, 2010 Uncommitted Credit Facilities [Member] USD ($)	Jul. 31, 2011 Treasury Notes Program [Member] EUR (€)	Jul. 31, 2010 Treasury Notes Program [Member] EUR (€)	Jul. 31, 2011 International Subsidiaries [Member] USD ($)	Jul. 31, 2010 International Subsidiaries [Member] USD ($)	Jul. 31, 2011 Standby Letters Of Credit [Member] USD ($)	Jul. 31, 2010 Standby Letters Of Credit [Member] USD ($)
Credit facility expiration period							5
Credit facilities, maximum borrowing capacity			€ 45.6				$ 250.0				€ 100.0	€ 100.0
Credit facilities, maturity date							April 2, 2013
Credit facilities, amount outstanding	0	11.4	0	0	0	0	50.0		13.1				0	0	11.4	0
Credit facility, remaining borrowing capacity							$ 238.6	$ 180.0	$ 56.9	$ 70.0
Short-term borrowings, weighted average interest rate								0.60%
Short-term borrowings, weighted average interest rate outstanding									0.90%
Number of uncommitted credit facilities	3