Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

+ Details

Name:	invest_DerivativeNotionalAmount
Namespace Prefix:	invest_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the final settlement amount of derivative instrument payable during the period.

+ References

No definition available.

+ Details

Name:	lpg_DerivativeInstrumentFinalSettlementAmount
Namespace Prefix:	lpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num: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_DerivativeLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=64837297&loc=SL5579245-113959

+ Details

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

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

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

- Details

Name:	us-gaap_CounterpartyNameAxis=lpg_CitibankN.A.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=lpg_IngBankN.V.Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CounterpartyNameAxis=lpg_CommonwealthBankOfAustraliaMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=lpg_InterestRateSwap1.21DueMarch2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DerivativeInstrumentRiskAxis=lpg_InterestRateSwap1.16DueMarch2022Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Financial Instruments and Fair Value Disclosures (Swaps) (Details) $ in Millions	Dec. 31, 2016 USD ($)	Jun. 30, 2016 USD ($) item	Oct. 31, 2015 USD ($)	Sep. 30, 2015 USD ($)
Interest rate swaps \| Royal Bank of Scotland plc (RBS)
Derivative Instruments
Final settlement amount	$ 8.1
Interest rate swaps \| Citibank N.A.
Derivative Instruments
Number of interest rate swaps \| item		2
Fixed interest rate (as a percent)			1.38%	1.93%
Nominal value			$ 128.6	$ 200.0
Interest rate swaps \| ING Bank N. V. Member
Derivative Instruments
Fixed interest rate (as a percent)				2.00%
Nominal value				$ 50.0
Interest rate swaps \| CBA
Derivative Instruments
Fixed interest rate (as a percent)			1.43%
Nominal value			$ 85.7
1.21% interest rate swap due March 2022 \| Citibank N.A.
Derivative Instruments
Fixed interest rate (as a percent)		1.21%
Nominal value		$ 73.0
1.16% interest rate swap due March 2022 \| Citibank N.A.
Derivative Instruments
Fixed interest rate (as a percent)		1.16%
Nominal value		$ 30.0