Other Borrowings - Additional Information (Detail) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021	Jun. 30, 2021
Debt [Line Items]
FHLB advances	$ 2,000	$ 0
Other Short-term Borrowings	40	35
Short-term Debt	3,979	727
Senior Notes	316	318
Notes Payable	915	457
Long-term Debt	1,231	775
Other borrowings	5,210	1,502
Customer repurchase agreements	79	17
Federal Funds Purchased	1,860	675
Notes Payable, Other Payables
Debt [Line Items]
Debt Issuance Cost	5		$ 3
Debt Instrument, Face Amount	$ 300		$ 242
Debt Instrument, Interest Rate Terms	LIBOR plus 5.50%
Senior Notes
Debt [Line Items]
Debt Instrument, Face Amount	$ 300
Debt Instrument, Interest Rate, Stated Percentage	6.50%
Credit Linked Notes Maturing July 2059
Debt [Line Items]
Debt Issuance Cost	$ 3
Debt Instrument, Face Amount	228
Credit Linked Notes Maturing April 2052
Debt [Line Items]
Debt Issuance Cost	3
Debt Instrument, Face Amount	194
Federal Home Loan Bank Advances [Member]
Debt [Line Items]
Additional available credit with the entity	7,800
FRB [Member]
Debt [Line Items]
Additional available credit with the entity	4,700	$ 3,400
Unsecured Credit Facility [Member]
Debt [Line Items]
Secured borrowing credit line	3,400
Warehouse Agreement Borrowings
Debt [Line Items]
Additional available credit with the entity	$ 1,000