Other liabilities - Movement In Unfavorable Drilling Contracts (Details) - USD ($) $ in Millions	3 Months Ended
Jun. 30, 2024	Mar. 31, 2024
Movement in Unfavorable Drilling Contracts [Roll Forward]
Net carrying amount, beginning balance	$ 41	$ 52
Amortization	(7)	(11)
Net carrying amount, ending balance	$ 34	$ 41

The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
-Section 45
-Paragraph 28
-Subparagraph (b)
-SubTopic 10
-Topic 230
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482740/230-10-45-28

Name:	us-gaap_AdjustmentForAmortization
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration