Derivative instruments - Impact of Hedging Derivatives Used in Net Investment Hedging Relationships (Details) - FX contracts - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Jun. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) recognized in accumulated OCI on derivatives	$ 201	$ (62)	$ (289)	$ 221	$ 103
Net interest revenue
Derivative Instruments, Gain (Loss) [Line Items]
Gain or (loss) reclassified from accumulated OCI into income	$ 0	$ 0	$ 0	$ 0	$ 0

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.

No definition available.

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Amount, before tax and reclassification, of gain (loss) from derivative designated and qualifying as net investment hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CCC
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109998896-113959

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Amount, before tax, of reclassification from accumulated other comprehensive income (AOCI) for gain (loss) from derivative designated and qualifying as net investment hedge.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 4CCC
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=125515794&loc=SL109998896-113959

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