The consideration associated with the acquisition of a vessel and the related time charter.

No definition available.

Name:	dlng_ConsiderationToAcquireValueOfVesselAndTimeCharter
Namespace Prefix:	dlng_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The LNG carrier's capacity in cubic meters.

+ References

No definition available.

+ Details

Name:	dlng_LNGCarrierCapacity
Namespace Prefix:	dlng_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The date the LNG carrier was delivered to the Company.

+ References

No definition available.

+ Details

Name:	dlng_LNGCarrierDeliveryDate
Namespace Prefix:	dlng_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of vessels owned and/ or to be acquired by the partnership.

+ References

No definition available.

+ Details

Name:	dlng_NumberVessels
Namespace Prefix:	dlng_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

End date of right of exercising a purchase option,in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	dlng_PurchaseOptionPeriodExpirationDate
Namespace Prefix:	dlng_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

The type of vessel.

+ References

No definition available.

+ Details

Name:	dlng_VesselType
Namespace Prefix:	dlng_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount of unused borrowing capacity under the long-term financing arrangement that is available to the entity as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

Portion of the carrying amount as of the balance sheet date of obligations due all related parties that is payable after one year or beyond the normal operating cycle if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.23)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(k)(1))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

+ Details

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

- Definition

The number of units or percentage investment held in the subsidiary by the limited liability company or limited partnership.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 946
-SubTopic 320
-Section S99
-Paragraph 9
-URI http://asc.fasb.org/extlink&oid=50485924&loc=d3e611443-123010

+ Details

Name:	us-gaap_SubsidiaryOfLimitedLiabilityCompanyOrLimitedPartnershipOwnershipInterest
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_RelatedPartyTransactionAxis=dlng_AmendedOmnibusAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=dlng_LegalRightMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

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

- Details

Name:	us-gaap_TypeOfArrangementAxis=dlng_LegalRight2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dlng_LenaRiverMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dlng_OptionalVesselsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dlng_CleanOceanAndCleanPlanetMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_TypeOfArrangementAxis=dlng_ExtensionOfPurchaseOptionExerciseDeadlineMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=dlng_CleanHorizonAndCleanVisionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Transactions with related parties - Optional Vessel acquisitions from Sponsor/ Omnibus Agreement (Details) $ in Thousands	1 Months Ended	3 Months Ended		12 Months Ended
	Feb. 06, 2018	Mar. 30, 2017	Apr. 12, 2016	Dec. 31, 2017 USD ($)	Dec. 21, 2015 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Debt instrument, remaining borrowing capacity				$ 0		$ 0
Amended Omnibus Agreement \| Legal right to acquire Sponsor's interests in Additional Optional Vessels
Related Party Transaction [Line Items]
Percentage of ownership in entity			49.00%
LNG Carrier Capacity			172,000
Number Of Vessels			5
Vessel Type			ARC7 LNG carrier
$200 Million Term Loan Facility
Related Party Transaction [Line Items]
Debt instrument, remaining borrowing capacity							$ 66,700
Dynagas Holding Ltd \| Legal right to acquire Sponsor's interests in Initial Optional Vessels
Related Party Transaction [Line Items]
Number Of Vessels				4
Lena River
Related Party Transaction [Line Items]
Percentage of ownership in entity					100.00%
LNG Carrier Capacity				155,000
Delivery Date				December 2015
Consideration for vessel and related time charter					$ 240,000
Lena River \| Dynagas Holding Ltd
Related Party Transaction [Line Items]
Principal amount due					$ 35,000
Additional Optional Vessels
Related Party Transaction [Line Items]
Delivery Date				late 2017 and early 2018
Number Of Vessels				2
Clean Ocean and Clean Planet \| Extension of the purchase option exercise deadline
Related Party Transaction [Line Items]
Number Of Vessels		2
Purchase option period, Expiration date		Mar. 31, 2018
Clean Horizon and Clean Vision \| Subsequent Event \| Extension of the purchase option exercise deadline
Related Party Transaction [Line Items]
Purchase option period, Expiration date	Dec. 31, 2018