Amount of required monthly rental payments for operating leases.

No definition available.

Name:	dmlp_OperatingLeasesFutureMonthlyPayments
Namespace Prefix:	dmlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

A tenant improvement allowance associated with an operating lease.

+ References

No definition available.

+ Details

Name:	dmlp_TenantImprovementAllowance
Namespace Prefix:	dmlp_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

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

- Definition

Term of lessee's operating lease, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=77888426&loc=SL77918673-209980

+ Details

Name:	us-gaap_LesseeOperatingLeaseTermOfContract
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Details

Name:	us-gaap_LeaseArrangementTypeAxis=dmlp_OfficeLeaseMember
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:

Note 4 - Commitments and Contingencies (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Apr. 17, 2017
Tenant Improvement Allowance				$ 702,000
Operating Leases, Rent Expense, Total	$ 345,000	$ 385,000	$ 272,000
Office Lease [Member]
Lessee, Operating Lease, Term of Contract				10 years 270 days
Office Lease [Member] \| Minimum [Member]
Operating Leases, Future Monthly Payments				$ 25,000
Office Lease [Member] \| Maximum [Member]
Operating Leases, Future Monthly Payments				$ 30,000