Commitments, Contingent Liabilities and Guarantees - Summary of Significant Commitments (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Commitments to extend credit
Long-term Purchase Commitment
Commitments	$ 77,081	$ 74,499
Forward contracts related to residential mortgage loans held for sale
Long-term Purchase Commitment
Commitments	3,395	2,903
Letters of credit
Long-term Purchase Commitment
Commitments	1,858	1,982
Purchase obligations
Long-term Purchase Commitment
Commitments	161	195
Capital expenditures
Long-term Purchase Commitment
Commitments	93	75
Capital commitments for private equity investments
Long-term Purchase Commitment
Commitments	$ 91	$ 83