Subsequent Events (Details) $ in Millions	Nov. 07, 2017 USD ($)
Subsequent Events
Repayment of debt	$ 30.1
2017 Bridge Loan
Subsequent Events
Repayment of debt	30.1
2017 Bridge Loan \| Subsequent events
Subsequent Events
Repayment of debt	$ 30.1
Refinanced Corsair Loan \| Subsequent events
Subsequent Events
Stated rate (as a percent)	4.90%
Estimated financing cost to be incurred	$ 0.1
Monthly brokerage commission (as a percent)	1.25%
Brokerage commission fee on exercised purchase option excluding buyer deposit (as a percent)	1.00%
Periodic principal payment amount	$ 0.3
Principal payment frequency	monthly
Balloon payment amount	$ 13.0
Corsair LPG Transport LLC \| Subsequent events
Subsequent Events
Number of years of vessel	3 years
Value of vessel transferred	$ 65.0
Term of Charter Agreement	12 years
Period until purchase option exercisable	2 years
Proceeds from sale of vessel	$ 52.0
Deposit held by purchaser	$ 13.0

Represents the brokerage commission fee on exercised purchase option excluding deposit.

No definition available.

Name:	lpg_BrokerageCommissionFeeOnExercisedPurchaseOptionExcludingDepositPercentage
Namespace Prefix:	lpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the amount of balloon payment.

+ References

No definition available.

+ Details

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

- Definition

Represents the deposit value held by the buyer from sale of property, plant and equipment.

+ References

No definition available.

+ Details

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

- Definition

The estimated amount of financing costs.

+ References

No definition available.

+ Details

Name:	lpg_EstimatedFinancingCostsToBeIncurred
Namespace Prefix:	lpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The monthly brokerage commission percentage.

+ References

No definition available.

+ Details

Name:	lpg_MonthlyBrokerageCommissionPercentage
Namespace Prefix:	lpg_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Represents the number of year of vessel.

+ References

No definition available.

+ Details

Name:	lpg_NumberOfYearsOldOfVessel
Namespace Prefix:	lpg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of year until the purchase option becomes exercisable.

+ References

No definition available.

+ Details

Name:	lpg_NumberOfYearsUntilPurchaseOptionExercisable
Namespace Prefix:	lpg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the value of property plant and equipment transferred.

+ References

No definition available.

+ Details

Name:	lpg_PropertyPlantAndEquipmentValueTransferred
Namespace Prefix:	lpg_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the term of the bareboat charter agreement.

+ References

No definition available.

+ Details

Name:	lpg_TermOfBareboatCharterAgreement
Namespace Prefix:	lpg_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of the frequency of periodic payments (monthly, quarterly, annual).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=6479336&loc=d3e64711-112823

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 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentFrequencyOfPeriodicPayment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ 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(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of the required periodic payments applied to principal.

+ 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)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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

- Definition

The cash inflow from the sale of long-lived, physical assets that are used in the normal conduct of business to produce goods and services and not intended for resale.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=66902209&loc=d3e3179-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Investing Activities
-URI http://asc.fasb.org/extlink&oid=6516133

+ Details

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

- Definition

The cash outflow during the period from the repayment of aggregate short-term and long-term debt. Excludes payment of capital lease obligations.

+ References

No definition available.

+ Details

Name:	us-gaap_RepaymentsOfDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

Name:	us-gaap_SubsequentEventLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=lpg_DebtFacility2017BridgeLoanMember
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:

- Details

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

- Details

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