Short-Term Borrowings - Schedule of Short-term Borrowings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Short-term Debt [Line Items]
Year-end balance	$ 3,400	$ 2,549
Trading Liabilities
Short-term Debt [Line Items]
Average balance	555	301	$ 480
Year-end balance	550	509	335
Maximum month-end outstanding	$ 767	$ 509	$ 700
Average rate for the year	4.22%	4.16%	2.56%
Average rate at year-end	4.20%	4.48%	3.67%
Federal Funds Purchased
Short-term Debt [Line Items]
Average balance	$ 420	$ 349	$ 699
Year-end balance	259	302	400
Maximum month-end outstanding	$ 626	$ 622	$ 1,023
Average rate for the year	5.34%	5.12%	1.56%
Average rate at year-end	4.40%	5.40%	4.40%
Securities Sold Under Agreements to Repurchase
Short-term Debt [Line Items]
Average balance	$ 1,720	$ 1,426	$ 881
Year-end balance	2,096	1,921	1,013
Maximum month-end outstanding	$ 2,096	$ 1,957	$ 1,211
Average rate for the year	3.83%	3.66%	0.77%
Average rate at year-end	3.23%	3.98%	2.19%
Other Short-term Borrowings
Short-term Debt [Line Items]
Average balance	$ 781	$ 2,688	$ 229
Year-end balance	1,045	326	1,093
Maximum month-end outstanding	$ 2,067	$ 7,476	$ 1,093
Average rate for the year	5.38%	5.19%	2.26%
Average rate at year-end	4.48%	5.36%	4.30%