Noncontrolling interest in number of suppliers.

No definition available.

Name:	dorm_NoncontrollingInterestInNumberOfSuppliers
Namespace Prefix:	dorm_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Date which lease or group of leases is set to expire, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Present value of lessee's discounted obligation for lease payments from operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

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

- Definition

Amount of lessee's right to use underlying asset under operating lease.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 45
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=77888419&loc=SL77918627-209977

+ Details

Name:	us-gaap_OperatingLeaseRightOfUseAsset
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Rental expense for the reporting period incurred under operating leases, including minimum and any contingent rent expense, net of related sublease income.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 840
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=77902758&loc=d3e41499-112717

+ Details

Name:	us-gaap_OperatingLeasesRentExpenseNet
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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_RelatedPartyTransactionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

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Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=dorm_ExecutiveChairmanAndFamilyMembersMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=dorm_JointVentureMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_StatementScenarioAxis=srt_ScenarioForecastMember
Namespace Prefix:
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Related Party Transactions - Additional Information (Detail) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 28, 2019 USD ($) Supplier	Dec. 28, 2019 USD ($)	Dec. 29, 2018 USD ($)
Related Party Transaction [Line Items]
Rental payments based upon the terms of the lease			$ 1,600
Right-of-use asset	$ 33,870
Lease liabilities	$ 36,716
Lease expiration date	Dec. 31, 2022
Canada [Member]
Related Party Transaction [Line Items]
Rental payments based upon the terms of the lease			$ 500
Lease expiration date	Apr. 30, 2019
Steven L. Berman and Other Family Members [Member]
Related Party Transaction [Line Items]
Right-of-use asset	$ 4,900
Lease liabilities	$ 4,900
Joint Venture [Member]
Related Party Transaction [Line Items]
Minority interests in number of suppliers \| Supplier	2
Scenario, Forecast [Member]
Related Party Transaction [Line Items]
Rental payments based upon the terms of the lease		$ 1,600
Scenario, Forecast [Member] \| Canada [Member]
Related Party Transaction [Line Items]
Rental payments based upon the terms of the lease		$ 200