Aggregate cost for capped call transactions in connection with issuance of convertible debt instruments.

No definition available.

Name:	hlx_AggregateCostDebtInstrumentConvertibleAssociatedCappedCallTransactionsCost
Namespace Prefix:	hlx_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Cap price stated in the contract for options indexed to the issuer's equity shares.

+ References

No definition available.

+ Details

Name:	hlx_CapCallCapPrice
Namespace Prefix:	hlx_
Data Type:	dtr-types:perShareItemType
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_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The number of issuer's shares to which the option contract is indexed.

+ References

+ Details

Name:	us-gaap_OptionIndexedToIssuersEquityIndexedShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Exercise or strike price stated in the contract for options indexed to the issuer's equity shares.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 40
-Section 50
-Paragraph 5
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=123477628&loc=d3e90205-114008

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 480
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (f)(1)
-URI http://asc.fasb.org/extlink&oid=109262807&loc=d3e22047-110879

+ Details

Name:	us-gaap_OptionIndexedToIssuersEquityStrikePrice1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:perShareItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_OptionIndexedToIssuersEquityTypeAxis=us-gaap_CallOptionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Long-Term Debt - 2026 Capped Calls (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Debt Instrument [Line Items]
Aggregate cost of capped call transactions	$ 10,625		$ 10,625
2026 Capped Calls
Debt Instrument [Line Items]
Aggregate number of common shares subject to capped calls		28,675,900
Initial strike price		$ 6.97
Initial cap price		$ 8.42
Aggregate cost of capped call transactions		$ 10,600