Financial Instruments Subject to Off-Balance Sheet Credit Risk (Summary of the Fair Value of Client Securities Available to Utilize as Collateral and Amounts Pledged) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Securities Financing Transaction [Line Items]
Fair value of client securities available to be pledged	$ 120,306	$ 84,006
Total collateral pledged to third parties	31,422	23,018
Fulfillment of Requirements with the Options Clearing Corporation [Member]
Securities Financing Transaction [Line Items]
Total collateral pledged to third parties	16,829	10,222
Fulfillment of Client Short Sales [Member]
Securities Financing Transaction [Line Items]
Total collateral pledged to third parties	5,934	6,274
Securities Lending to Other Broker-Dealers [Member]
Securities Financing Transaction [Line Items]
Total collateral pledged to third parties	6,269	6,522
Collateral For Short-Term Borrowings [Member]
Securities Financing Transaction [Line Items]
Total collateral pledged to third parties	2,390	0
Fully-Paid Client Securities [Member]
Securities Financing Transaction [Line Items]
Total collateral pledged to third parties	$ 118	$ 183