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Marketable securities - Gross Realized Gains and Losses Related to Marketable Securities (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020
Gain (Loss) on Securities [Line Items]
Total unrealized gain / (loss) on marketable securities	$ 5	$ (6)
Seadrill Partners - Common units - unrealized loss on marketable securities
Gain (Loss) on Securities [Line Items]
Total unrealized gain / (loss) on marketable securities	0	(2)
Archer - unrealized gain / (loss) on marketable securities
Gain (Loss) on Securities [Line Items]
Total unrealized gain / (loss) on marketable securities	$ 5	$ (4)

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- Definition

Amount of realized gain (loss) on investment in marketable security, including other-than-temporary impairment (OTTI).

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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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