Income Taxes - Operating and capital loss carryforwards available (Details) - Dec. 31, 2024 £ in Millions, $ in Millions	USD ($)	GBP (£)
U.S. \| Expiring 2025 - 2041
Operating and capital loss carryforwards [Line Items]
Operating loss carryforwards	$ 8
United Kingdom
Operating and capital loss carryforwards [Line Items]
Operating loss carryforwards	$ 35	£ 28

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.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-3

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration