Contingent liabilities, commitments and guarantees - Schedule of Contingent Liabilities (Details) - GBP (£) £ in Millions	Jun. 30, 2020	Dec. 31, 2019
Contingent liabilities
Acceptances and endorsements	£ 141	£ 74
Other items serving as direct credit substitutes	370	366
Performance bonds and other transaction-related contingencies	2,157	2,454
Total other contingent liabilities	2,527	2,820
Total contingent liabilities	£ 2,668	£ 2,894

The amount of the estimated financial effect of contingent liabilities. [Refer: Contingent liabilities [member]]

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Name IAS
-Number 37
-IssueDate 2019-01-01
-Paragraph 86
-Subparagraph a
-URI http://eifrs.ifrs.org/eifrs/xifrs-link?type=IAS&num=37&code=ifrs-tx-2019-en-r&anchor=para_86_a&doctype=Standard
-URIDate 2019-03-27

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Namespace Prefix:	ifrs-full_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant