Reorganization under Chapter 11 Bankruptcy, Issuance of Common Stock, Diluted, Employee Incentive Plan, Percent

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Total number of common shares of an entity that have been sold or granted to shareholders (includes common shares that were issued, repurchased and remain in the treasury). These shares represent capital invested by the firm's shareholders and owners, and may be all or only a portion of the number of shares authorized. Shares issued include shares outstanding and shares held in the treasury.

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Aggregate par or stated value of issued nonredeemable common stock (or common stock redeemable solely at the option of the issuer). This item includes treasury stock repurchased by the entity. Note: elements for number of nonredeemable common shares, par value and other disclosure concepts are in another section within stockholders' equity.

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Face (par) amount of debt instrument at time of issuance.

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Amount of reorganization items related to discharge of claims and liabilities upon emergence from bankruptcy.

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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.

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Amount of prepetition liabilities to be settled in cash.

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Previous Chapter 11 Proceedings - Additional Information (Details) - USD ($)	Jul. 02, 2018	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 26, 2018	Sep. 12, 2017
Fresh-Start Adjustment [Line Items]
Amount of new cash commitments in the form of new notes and equity	$ 1,000,000,000.0				$ 1,100,000,000	$ 1,100,000,000
Common shares, issued (in shares)	100,000,000	100,384,435	100,234,973	100,000,000
Common stock, value issued		$ 10,000,000	$ 10,000,000	$ 10,000,000
Fully diluted, reserved for Employee Incentive Plan	10.00%
Senior secured notes \| Secured Debt
Fresh-Start Adjustment [Line Items]
Debt, face amount	$ 880,000,000
Commitment Parties [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	23,750,000
Common stock, value issued	$ 200,000,000
Commitment Parties and Notes Right Offering Subscribers [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	54,625,000
Holders of General Unsecured Claims [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	14,250,000
Old Seadrill Limited and Seadrill Limited 510(b) [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	1,900,000
Other Commitment Parties [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	475,000
Hemen [Member]
Fresh-Start Adjustment [Line Items]
Common shares, issued (in shares)	5,000,000
Financial guarantee \| Unsecured bonds
Fresh-Start Adjustment [Line Items]
Extinguished financial guarantees	$ 2,400,000,000
Financial guarantee \| Newbuild obligation
Fresh-Start Adjustment [Line Items]
Extinguished financial guarantees	1,000,000,000.0
Financial guarantee \| Unsecured interest rate and currency swaps
Fresh-Start Adjustment [Line Items]
Extinguished financial guarantees	$ 250,000,000