Borrowings (Details) - Unsecured revolving credit facility	3 Months Ended
Oct. 31, 2020 USD ($)
Debt Instrument
Remaining borrowing capacity	$ 100,000,000.0
Unsecured revolving credit facility maturing July 2022
Debt Instrument
Maximum borrowing capacity	500,000,000.0
Remaining borrowing capacity	$ 292,300,000
Revolving credit agreement (term)	364 days
Increase to borrowing capacity	$ 100,000,000.0
Extension term (term)	1 year

Debt Instrument Extension Term

No definition available.

Name:	dci_DebtInstrumentExtensionTerm
Namespace Prefix:	dci_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line of Credit Facility, Increase (Decrease) To Borrowing Capacity

+ References

No definition available.

+ Details

Name:	dci_LineOfCreditFacilityIncreaseDecreaseToBorrowingCapacity
Namespace Prefix:	dci_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Revolving Credit Agreement Term

+ References

No definition available.

+ Details

Name:	dci_RevolvingCreditAgreementTerm
Namespace Prefix:	dci_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- 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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-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=120391452&loc=d3e13212-122682

+ 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

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dci_UnsecuredRevolvingCreditFacilityMaturingJuly2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: