Borrowings - Narrative (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Debt Instrument [Line Items]
Securities sold under customer repurchase agreements	$ 454	$ 436
Debt instrument, collateral amount	30,000
Asset Pledged as Collateral | Securities Assets
Debt Instrument [Line Items]
Securities sold under customer repurchase agreements	508	496
Unsecured Debt
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	100
Line of credit facility, remaining borrowing capacity	85
Notes Payable To FHLB | Secured Debt | Asset Pledged as Collateral
Debt Instrument [Line Items]
Debt instrument, collateral amount	24,000
Other secured financings | Secured Debt | Federal Reserve Bank of Richmond
Debt Instrument [Line Items]
Debt instrument, collateral amount	6,000
Line of credit facility, additional borrowing capacity	4,800
Long-term line of credit	$ 0	$ 0