Borrowings - Short-term Borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Short-term Debt	$ 5,292	$ 6,092
Federal Funds Purchased
Short-term Debt [Line Items]
Short-term Debt	0	79
Securities Sold under Agreements to Repurchase
Short-term Debt [Line Items]
Short-term Debt	2,435	1,221
FHLB Advances
Short-term Debt [Line Items]
Short-term Debt	0	2,649
Dealer Collateral
Short-term Debt [Line Items]
Short-term Debt	318	385
Master Notes
Short-term Debt [Line Items]
Short-term Debt	808	621
Securities sold short
Short-term Debt [Line Items]
Short-term Debt	1,731	1,115
Other Short-term Borrowings
Short-term Debt [Line Items]
Short-term Debt	$ 0	$ 22