Earnings Per Share - Shares Included in Diluted Calculations Assuming Earnings (Details) - shares shares in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Earnings Per Share [Abstract]
Diluted shares (as reported)	149,935	148,863
Share-based awards	1,093	722
Total	151,028	149,585

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU) including nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents.

No definition available.

+ Details

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Namespace Prefix:	hlx_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- References

No definition available.

+ Details

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- Definition

This element represents nonvested share-based payment awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). Basic and dilutive earnings per share are generally disclosed for such shares using the two-class method.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 68B
-URI http://asc.fasb.org/extlink&oid=121326447&loc=SL5498026-109256

+ Details

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Data Type:	xbrli:sharesItemType
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- Definition

The average number of shares or units issued and outstanding that are used in calculating diluted EPS or earnings per unit (EPU), determined based on the timing of issuance of shares or units in the period.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 260
-SubTopic 10
-Section 45
-Paragraph 16
-URI http://asc.fasb.org/extlink&oid=121326447&loc=d3e1505-109256

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Period Type:	duration