Loans, Lending Commitments and Related Allowance for Credit Losses - Modified Loans Held for Investment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 260	$ 147
Percent of total loans	0.20%	0.20%
Term Extension
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 220	$ 80
Percent of total loans	0.20%	0.10%
Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0	$ 67
Percent of total loans	0.00%	0.80%
Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 40	$ 0
Percent of total loans	0.50%	0.00%
Modified Terms
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 301	$ 607
Corporate | Single Modifications
Financing Receivable, Modified [Line Items]
Percent of total loans	0.00%	0.00%
Corporate | Term Extension
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 52	$ 17
Percent of total loans	0.70%	0.20%
Corporate | Term Extension | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	30 months	8 months
Corporate | Other-than-insignificant Payment Delay | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	0 months	0 months
Corporate | Principal Forgiveness | Single Modifications
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0	$ 0
Commercial real estate | Single Modifications
Financing Receivable, Modified [Line Items]
Percent of total loans	0.00%	0.00%
Commercial real estate | Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Percent of total loans	0.00%
Commercial real estate | Term Extension
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 127	$ 62
Percent of total loans	1.50%	0.70%
Commercial real estate | Term Extension | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	5 months	2 months
Commercial real estate | Term Extension | Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification		16 months
Commercial real estate | Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0	$ 67
Percent of total loans	0.00%	0.80%
Commercial real estate | Other-than-insignificant Payment Delay | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	0 months	8 months
Commercial real estate | Other-than-insignificant Payment Delay | Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification		16 months
Commercial real estate | Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 40	$ 0
Percent of total loans	0.50%	0.00%
Commercial real estate | Principal Forgiveness | Single Modifications
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0	$ 0
Commercial real estate | Principal Forgiveness | Multiple Modifications - Term Extension and Other-than-insignificant Payment Delay
Financing Receivable, Modified [Line Items]
Amortized Cost	0
Residential real estate | Single Modifications
Financing Receivable, Modified [Line Items]
Percent of total loans		0.00%
Residential real estate | Term Extension
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0	$ 1
Percent of total loans	0.00%	0.00%
Residential real estate | Term Extension | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification		4 months
Residential real estate | Other-than-insignificant Payment Delay | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification		0 months
Residential real estate | Principal Forgiveness | Single Modifications
Financing Receivable, Modified [Line Items]
Amortized Cost		$ 0
Securities-based lending and Other | Single Modifications
Financing Receivable, Modified [Line Items]
Percent of total loans	0.00%
Securities-based lending and Other | Term Extension
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 41	$ 0
Percent of total loans	0.00%	0.00%
Securities-based lending and Other | Term Extension | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	36 months
Securities-based lending and Other | Other-than-insignificant Payment Delay | Single Modifications
Financing Receivable, Modified [Line Items]
Weighted average term increase from modification	0 months
Securities-based lending and Other | Principal Forgiveness | Single Modifications
Financing Receivable, Modified [Line Items]
Amortized Cost	$ 0