Short-Term Borrowings - Summary of Short-Term Borrowings (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Short-term Debt [Line Items]
Short-term borrowings	$ 2,506	$ 2,124
Trading Liabilities
Short-term Debt [Line Items]
Average balance	480	540	$ 457
Short-term borrowings	335	426	353
Maximum month-end outstanding	$ 700	$ 685	$ 983
Average rate for the year	2.56%	1.11%	1.24%
Average rate at year-end	3.67%	1.62%	0.77%
Federal Funds Purchased
Short-term Debt [Line Items]
Average balance	$ 699	$ 949	$ 862
Short-term borrowings	400	775	845
Maximum month-end outstanding	$ 1,023	$ 1,037	$ 1,487
Average rate for the year	1.56%	0.12%	0.34%
Average rate at year-end	4.40%	0.10%	0.10%
Securities Sold Under Agreements to Repurchase
Short-term Debt [Line Items]
Average balance	$ 881	$ 1,235	$ 1,109
Short-term borrowings	1,013	1,247	1,187
Maximum month-end outstanding	$ 1,211	$ 1,615	$ 1,661
Average rate for the year	0.77%	0.30%	0.50%
Average rate at year-end	2.19%	0.11%	0.26%
Other Short-term Borrowings
Short-term Debt [Line Items]
Average balance	$ 229	$ 124	$ 626
Short-term borrowings	1,093	102	166
Maximum month-end outstanding	$ 1,093	$ 146	$ 4,061
Average rate for the year	2.26%	0.09%	0.84%
Average rate at year-end	4.30%	0.08%	0.09%