Loans and Allowance for Credit Losses - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) security loan loanSegment	Dec. 31, 2022 USD ($) security loan	Dec. 31, 2021 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Percentage of investment portfolio considered investment grade	99.00%
Marketable securities, unrealized gain (loss)	$ 6,190	$ 8,100
Number of securities in loss position | security	1,704	2,094
Number of loans and leases segments | loanSegment	2
Financing receivable, excluding accrued interest, after allowance for credit loss	$ 36,496	$ 32,053
Number of loans on non-accrual status | loan	3	0
Financing receivable, nonaccrual	$ 70
Sale of loans	506	$ 1,786	$ 172
Provision for credit losses	$ 46	20	$ (33)
Investment grade loans	87.00%
Speculative grade loans	11.00%
Speculative senior secured loans with BB or B rating	92.00%
Asset Pledged as Collateral
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, excluding accrued interest, after allowance for credit loss	$ 13,000	$ 10,170
Leveraged Loans
Financing Receivable, Credit Quality Indicator [Line Items]
Sale of loans	519
Provision for credit losses	$ (17)
Commercial and Financial
Financing Receivable, Credit Quality Indicator [Line Items]
Loans no longer meeting similar risk of collective pool | loan	3
Loans no longer meeting similar risk of collective pool, amount	$ 38
Allowance for credit loss	48
Collateralized loan obligations
Financing Receivable, Credit Quality Indicator [Line Items]
Payments to acquire loans receivable	$ 1,680
Commercial Real Estate
Financing Receivable, Credit Quality Indicator [Line Items]
Loans no longer meeting similar risk of collective pool | loan	4
Loans no longer meeting similar risk of collective pool, amount	$ 271