Revenue Recognition - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Disaggregation of Revenue [Line Items]
Cash and cash equivalents	$ 454	$ 413
Cash and investments segregated	388	432
Receivables from brokerage clients	1,260	1,084
Available for sale securities	594	825
Held to maturity securities	690	746
Bank loans	440	391
Securities lending revenue	76	112
Other interest revenue	39	13
Interest revenue	3,941	4,016
Bank deposits	(921)	(618)
Payables to brokerage clients	(73)	(75)
Other short-term borrowings	(103)	(86)
Federal Home Loan Bank borrowings	(330)	(304)
Long-term debt	(224)	(139)
Securities lending expense	(55)	(22)
Other interest expense	(2)	(2)
Interest expense	(1,708)	(1,246)
Net interest revenue	2,233	2,770
Total net revenues	4,740	5,116
Asset management and administration fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	1,348	1,118
Mutual funds, ETFs, and CTFs
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	758	585
Advice solutions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	503	453
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	87	80
Trading revenue
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	817	892
Commissions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	413	422
Order flow revenue
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	352	414
Principal transactions
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	52	56
Bank deposit account fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	183	151
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers	$ 159	$ 185