Debt Instrument, Number Of Tranches

No definition available.

Name:	dci_DebtInstrumentNumberOfTranches
Namespace Prefix:	dci_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Line Of Credit Facility, Additional Borrowing Capacity Under Certain Conditions

+ References

No definition available.

+ Details

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

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 1B
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	instant

- 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

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The fee, expressed as a percentage of the line of credit facility, for the line of credit facility regardless of whether the facility has been used.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any 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_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
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

The cash inflow from a debt initially having maturity due after one year or beyond the operating cycle, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=123570139&loc=d3e3255-108585

+ Details

Name:	us-gaap_ProceedsFromIssuanceOfLongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dci_UnsecuredRevolvingCreditFacilityPreviouslyMaturingJuly2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dci_A2510YearNoteDue2031Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=dci_A2127YearNoteDue2028Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ShortTermDebtTypeAxis=us-gaap_LineOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

Long-Term Debt (Narrative) (Details)	3 Months Ended	12 Months Ended
Long-Term Debt (Narrative) (Details)	Jul. 31, 2021 USD ($) tranche	Jul. 31, 2021 USD ($) tranche	Jul. 31, 2020 USD ($)	Jul. 31, 2019 USD ($)
Debt Instrument
Proceeds from long-term debt		$ 7,900,000	$ 262,400,000	$ 155,000,000.0
Senior Notes \| Unsecured revolving credit facility
Debt Instrument
Number of tranches (tranche) \| tranche	2	2
Senior Notes \| 2.50% fixed rate unsecured senior notes maturing 2031
Debt Instrument
Proceeds from long-term debt	$ 100,000,000
Debt instrument, term	10 years
Debt instrument interest rate (percent)	2.50%	2.50%
Senior Notes \| 2.12% fixed rate unsecured senior notes maturing 2028
Debt Instrument
Proceeds from long-term debt	$ 50,000,000
Debt instrument, term	7 years
Debt instrument interest rate (percent)	2.12%	2.12%
Line of credit
Debt Instrument
Borrowing capacity	$ 336,600,000	$ 336,600,000	$ 418,400,000
Unsecured revolving credit facility
Debt Instrument
Long-term remaining borrowing capacity	417,300,000	417,300,000
Unsecured revolving credit facility \| 1.29 % Variable rate unsecured credit facility maturing 2026
Debt Instrument
Borrowing capacity	$ 500,000,000	500,000,000
Unsecured revolving credit facility \| Minimum
Debt Instrument
Commitment fee (percent)	0.08%
Unsecured revolving credit facility \| Maximum
Debt Instrument
Commitment fee (percent)	0.25%
Multi-currency revolving credit facility \| Line of credit
Debt Instrument
Additional borrowing capacity on line of credit under certain conditions	$ 250,000,000	$ 250,000,000