Required periodic principal payments per loan year as a percentage of total principal.

No definition available.

Name:	hlx_DebtInstrumentPeriodicPrincipalPaymentPercentage
Namespace Prefix:	hlx_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum aggregate commitments with respect to an increase in the Revolving Credit Facility, additional term loans, or a combination thereof that may be requested under the Credit Agreement.

+ References

No definition available.

+ Details

Name:	hlx_MaximumAggregateCommitmentIncrease
Namespace Prefix:	hlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of amortization expense attributable to debt issuance costs.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28555-108399

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03(8))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04(8))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

+ Details

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

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

+ 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

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

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

- 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=75038535&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

+ Details

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

- Definition

Date when the debt instrument is scheduled to be fully repaid, in CCYY-MM-DD format.

+ References

+ Details

Name:	us-gaap_DebtInstrumentMaturityDate
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Difference between the fair value of payments made and the carrying amount of debt which is extinguished prior to maturity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12317-112629

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3602-108585

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 50
-Section 40
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=49170532&loc=d3e12355-112629

+ Details

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

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

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

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

- Definition

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

+ References

No definition available.

+ Details

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

- Definition

Amount of cash outflow for the payment of debt classified as other, maturing after one year or the operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=98514028&loc=d3e3291-108585

+ Details

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

- Details

Name:	us-gaap_LongtermDebtTypeAxis=hlx_TermLoanMaturingJune2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	hlx_DebtInstrumentPaymentScheduleAxis=hlx_PaymentPeriodOneMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	hlx_DebtInstrumentPaymentScheduleAxis=hlx_PaymentPeriodTwoMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	hlx_DebtInstrumentPaymentScheduleAxis=hlx_PaymentPeriodThreeMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_BaseRateMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_VariableRateAxis=us-gaap_LondonInterbankOfferedRateLIBORMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=hlx_TermLoanAndRevolvingLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=hlx_RevolvingCreditFacilityMaturingJune2020Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LongtermDebtTypeAxis=us-gaap_LetterOfCreditMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt - Credit Agreement (Details) - USD ($)		1 Months Ended	3 Months Ended
Long-Term Debt - Credit Agreement (Details) - USD ($)	Jun. 30, 2017	Mar. 31, 2018	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Debt Instrument [Line Items]
Principal amount		$ 512,400,000	$ 512,400,000
Repayment of term loan			61,468,000	$ 6,409,000
Loss on extinguishment of long-term debt			(1,105,000)	0
Amortization of debt issuance costs			935,000	$ 1,358,000
Term Loan Maturing June 2020
Debt Instrument [Line Items]
Principal amount	$ 100,000,000	36,032,000	$ 36,032,000		$ 97,500,000
Repayment of term loan		$ 61,000,000
Interest rate (as a percent)		6.13%	6.13%
Frequency of periodic payment	quarterly
Loss on extinguishment of long-term debt		$ (900,000)
Term Loan Maturing June 2020 \| First Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	5.00%
Term Loan Maturing June 2020 \| Second Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	10.00%
Term Loan Maturing June 2020 \| Third Loan Year
Debt Instrument [Line Items]
Periodic principal payment (as a percent)	15.00%
Term Loan Maturing June 2020 \| Base Rate
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.25%
Term Loan Maturing June 2020 \| LIBOR
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	4.25%
Term Loan and Revolving Loans
Debt Instrument [Line Items]
Maturity date	Jun. 30, 2020
Revolving Credit Facility Maturing June 2020
Debt Instrument [Line Items]
Borrowing capacity	$ 150,000,000
Additional commitments	$ 100,000,000
Available borrowing capacity		142,900,000	$ 142,900,000
Letters of credit issued		$ 3,000,000	$ 3,000,000
Commitment fee percentage	0.50%
Revolving Credit Facility Maturing June 2020 \| Base Rate \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	1.75%
Revolving Credit Facility Maturing June 2020 \| Base Rate \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	3.25%
Revolving Credit Facility Maturing June 2020 \| LIBOR \| Minimum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	2.75%
Revolving Credit Facility Maturing June 2020 \| LIBOR \| Maximum
Debt Instrument [Line Items]
Basis spread on variable rate (as a percent)	4.25%
Letter of Credit
Debt Instrument [Line Items]
Borrowing capacity	$ 25,000,000