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Summary Of Significant Accounting Policies - Recertification Costs And Deferred Dry Dock Costs (Details) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Dec. 31, 2017 | Dec. 31, 2016 | Dec. 31, 2015
Finite-Lived Intangible Assets [Line Items] |  |  |
Deferred dry dock costs, net | $ 12,368 | $ 14,766 |
Deferred dry dock costs accumulated amortization | 7,100 | 10,700 |
Dry dock amortization expense | $ 6,900 | $ 14,000 | $ 10,800
Minimum [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Dry dock amortization period | 30 months |  |
Dry dock recertification process period | 1 month |  |
Maximum [Member] |  |  |
Finite-Lived Intangible Assets [Line Items] |  |  |
Dry dock amortization period | 60 months |  |
Dry dock recertification process period | 2 months |  |

X
- Definition Carrying amount of accumulated amortization of deferred dry dock costs at the end of the reporting period + References No definition available. + Details
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Namespace Prefix: | hlx_
Data Type: | xbrli:monetaryItemType
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- Definition Deferred Dry Dock Costs, Net + References No definition available. + Details
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X
- Definition Expense related to amortization of deferred dry dock costs + References No definition available. + Details
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Balance Type: | debit
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X
- Definition The length of time in which the deferred dry dock costs are amortized. + References No definition available. + Details
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- Definition The length of time to complete the dry dock and recertification process. + References No definition available. + Details
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