Employee Benefit Plans - Share-Based Awards Granted (Details)	6 Months Ended
Jun. 30, 2018 $ / shares shares
Performance Share Units
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting Period	3 years
Maximum \| Performance Share Units
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting Percentage	200.00%
Minimum \| Performance Share Units
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Vesting Percentage	0.00%
January 2, 2018 - 33% per year over three years
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 02, 2018
Shares / Units \| shares	449,271
Grant Date Fair Value Per Share \| $ / shares	$ 7.54
Vesting Percentage	33.00%
Vesting Period	3 years
January 2, 2018 - 100% on January 2, 2021
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 02, 2018
Shares / Units \| shares	449,271
Grant Date Fair Value Per Share \| $ / shares	$ 10.44
Vesting Percentage	100.00%
Vesting Date	Jan. 02, 2021
January 2, 2018 - 100% on January 1, 2020
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Jan. 02, 2018
Shares / Units \| shares	8,247
Grant Date Fair Value Per Share \| $ / shares	$ 7.54
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2020
April 2, 2018 - 100% on January 1, 2020
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]
Date of Grant	Apr. 02, 2018
Shares / Units \| shares	11,064
Grant Date Fair Value Per Share \| $ / shares	$ 5.79
Vesting Percentage	100.00%
Vesting Date	Jan. 01, 2020

Grant date of share-based payment award.

No definition available.

Name:	hlx_ShareBasedCompensationArrangementByShareBasedPaymentAwardGrantDate
Namespace Prefix:	hlx_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Vesting date of share-based payment award.

+ References

No definition available.

+ Details

Name:	hlx_ShareBasedCompensationArrangementByShareBasedPaymentAwardVestingDate
Namespace Prefix:	hlx_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

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

- Definition

Period which an employee's right to exercise an award is no longer contingent on satisfaction of either a service condition, market condition or a performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardVestingPeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of grants made during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

The weighted average fair value at grant date for nonvested equity-based awards issued during the period on other than stock (or unit) option plans (for example, phantom stock or unit plan, stock or unit appreciation rights plan, performance target plan).

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)(iii)(1)
-URI http://asc.fasb.org/extlink&oid=109197908&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardEquityInstrumentsOtherThanOptionsGrantsInPeriodWeightedAverageGrantDateFairValue
Namespace Prefix:	us-gaap_
Data Type:	num:perShareItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of vesting of share-based compensation awards.

+ References

+ Details

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

- Details

Name:	us-gaap_AwardTypeAxis=us-gaap_PerformanceSharesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
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:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=hlx_GrantShareAmountMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=hlx_GrantShareAmountBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=hlx_GrantShareAmountCMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DeferredCompensationArrangementWithIndividualShareBasedPaymentsByTypeOfDeferredCompensationAxis=hlx_GrantShareAmountDMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: