Consolidated Balance Sheet (unaudited) (Parenthetical) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Statement of Financial Position [Abstract]
Cash and due from banks, allowance for credit loss	$ 2	$ 4
Interest-bearing deposits with banks, allowance for credit loss	2	3
Restricted cash	4,201	3,167
Debt securities, held-to-maturity, allowance for credit loss (less than)	1	1
Held-to-maturity, fair value	56,708	49,224
Debt securities, available-for-sale, amortized cost	99,338	105,141
Debt securities, available-for-sale, allowance for credit loss	10	11
Other assets, allowance for credit loss on accounts receivable	4	4
Other assets	1,313	1,009
Allowance for credit losses on lending related commitments	40	121
Other liabilities, fair value	433	1,110
Long-term debt, fair value	$ 400	$ 400
Preferred stock, par value (usd per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (shares)	100,000,000	100,000,000
Preferred stock, issued (shares)	45,826	45,826
Common stock, par value (usd per share)	$ 0.01	$ 0.01
Common stock, authorized (shares)	3,500,000,000	3,500,000,000
Common stock, issued (shares)	1,389,042,033	1,382,306,327
Treasury stock, common shares (shares)	563,220,970	495,542,796