Variable interest entities - Non-consolidated VIEs (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Assets	$ 452,621	$ 444,438
Liabilities	411,476	401,047
Securities – Available-for-sale | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	162	189
Liabilities	0	0
Maximum loss exposure	162	189
Other | Variable Interest Entity, Not Primary Beneficiary
Variable Interest Entity [Line Items]
Assets	2,384	2,385
Liabilities	623	543
Maximum loss exposure	$ 3,022	$ 2,946