Note 1 - General and Summary of Significant Accounting Policies (Details Textual) shares in Thousands, $ in Thousands	12 Months Ended
Dec. 31, 2020 USD ($) shares	Dec. 31, 2019 USD ($)
Number Of Counties In Which Entity Operates	587
Number of States in which Entity Operates	27
Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount (in shares) \| shares	0
Accounts Receivable, Allowance for Credit Loss, Current	$ 0
Future Net Revenues To Proved Oil And Natural Gas Reserves Discount Percentage	10.00%
Impairment of Oil and Gas Properties	$ 0	$ 0
Gain (Loss) Recognition Upon Disposition of Oil and Gas, Minimum Percent of Reserves	25.00%
Texas Franchise Tax Rate	0.75%
Royalty Revenue [Member]
Revenue Allocated To General Partner Percentage	4.00%
Net Profits Interests [Member]
Revenue Allocated To General Partner Percentage	1.00%

The discount percentage for future net revenues to proved oil and natural gas reserves.

No definition available.

Name:	dmlp_FutureNetRevenuesToProvedOilAndNaturalGasReservesDiscountPercentage
Namespace Prefix:	dmlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Gain or loss recognition upon disposition of oil and gas involving greater than the stated percentage of reserves.

+ References

No definition available.

+ Details

Name:	dmlp_GainLossRecognitionUponDispositionOfOilAndGasMinimumPercentOfReserves
Namespace Prefix:	dmlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of counties the entity operates in.

+ References

No definition available.

+ Details

Name:	dmlp_NumberOfCountiesInWhichEntityOperates
Namespace Prefix:	dmlp_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

The percentage of revenue allocated to the general partner.

+ References

No definition available.

+ Details

Name:	dmlp_RevenueAllocatedToGeneralPartnerPercentage
Namespace Prefix:	dmlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the Texas franchise tax rate.

+ References

No definition available.

+ Details

Name:	dmlp_TexasFranchiseTaxRate
Namespace Prefix:	dmlp_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of allowance for credit loss on accounts receivable, classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(4)
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=121611835&loc=d3e5074-111524

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=121599878&loc=SL82895884-210446

+ Details

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

- Definition

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

+ Details

Name:	us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The expense recorded to reduce the value of oil and gas assets consisting of proved properties and unproved properties as the estimate of future successful production from these properties is reduced.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 360
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=109226691&loc=d3e2921-110230

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3602-108585

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 932
-SubTopic 360
-Section 35
-Paragraph 11
-URI http://asc.fasb.org/extlink&oid=66906256&loc=d3e66150-109466

+ Details

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

- Definition

The number of states the entity operates in as of the balance sheet date.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfStatesInWhichEntityOperates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=dmlp_RoyaltyRevenueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AccountsNotesLoansAndFinancingReceivableByReceivableTypeAxis=dmlp_NetProfitsInterestsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: