Commitments, Contingent Liabilities and Guarantees - Summary of Significant Commitments (Details) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Commitments to extend credit
Long-term Purchase Commitment
Commitments	$ 72,020	$ 75,696
Forward contracts related to residential mortgage loans held for sale
Long-term Purchase Commitment
Commitments	4,085	2,901
Letters of credit
Long-term Purchase Commitment
Commitments	2,158	2,137
Purchase obligations
Long-term Purchase Commitment
Commitments	139	113
Capital expenditures
Long-term Purchase Commitment
Commitments	99	84
Capital commitments for private equity investments
Long-term Purchase Commitment
Commitments	$ 80	$ 75