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v3.20.4

Investment in associated companies - Ownership Percentage (Details) | Dec. 31, 2020 | Dec. 31, 2019 | Aug. 31, 2019 | Dec. 31, 2018 | Jul. 01, 2018
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Seabras Sapura |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% | 50.00% |  |  |
Seabras Sapura | Joint Venture Partner |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% |  |  |  |
SeaMex |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% | 50.00% |  | 50.00% | 50.00%
SeaMex | Joint Venture Partner |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% |  |  |  |
Sonadrill |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% | 50.00% |  | 0.00% | 0.00%
Sonadrill | Joint Venture Partner |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% |  |  |  |
Gulfdrill |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% | 50.00% | 50.00% | 0.00% | 0.00%
Gulfdrill | Joint Venture Partner |  |  |  |  |
Schedule of Equity Method Investments [Line Items] |  |  |  |  |
Ownership percentage | 50.00% |  |  |  |

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- Definition The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a)(1) -URI http://asc.fasb.org/extlink&oid=114001798&loc=d3e33918-111571 + Details
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- 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
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