Fair Value - Schedule of Carrying Values and Estimated Fair Values for Financial Instruments (Details) - USD ($) $ in Millions	Jun. 30, 2023	Dec. 31, 2022
Financial Assets
Investment in marketable equity securities	$ 76	$ 95
Investment securities available for sale	11,894	8,995
Investment securities held to maturity	10,201	10,279
Interest rate & other derivative — non-qualifying hedges	758	159
Financial Liabilities
Fair value of derivative financial instruments	825	486
Reported Value Measurement
Financial Assets
Cash and due from banks	917	518
Interest earning deposits at banks	37,846	5,025
Securities purchased under agreements to resell	298
Investment in marketable equity securities	76	95
Investment securities available for sale	11,894	8,995
Investment securities held to maturity	10,201	10,279
Loans held for sale	115	52
Net loans	129,288	67,720
Accrued interest receivable	732	329
Federal Home Loan Bank stock	119	197
Mortgage servicing rights	25	25
Interest rate & other derivative — non-qualifying hedges	758	159
Financial Liabilities
Deposits with no stated maturity	124,894
Deposits with no stated maturity		78,798
Time deposits	16,270	10,610
Credit balances of factoring clients	1,067	995
Securities sold under customer repurchase agreements	454	436
Other short-term debt		1,750
Long-term borrowings	39,679	4,452
Accrued interest payable	121	57
Fair value of derivative financial instruments	825	486
Estimate of Fair Value Measurement
Financial Assets
Cash and due from banks	917	518
Interest earning deposits at banks	37,846	5,025
Securities purchased under agreements to resell	298
Investment in marketable equity securities	76	95
Investment securities available for sale	11,894	8,995
Investment securities held to maturity	8,652	8,795
Loans held for sale	115	49
Net loans	126,813	64,312
Accrued interest receivable	732	329
Federal Home Loan Bank stock	119	197
Mortgage servicing rights	47	47
Interest rate & other derivative — non-qualifying hedges	758	159
Financial Liabilities
Deposits with no stated maturity	124,894
Deposits with no stated maturity		78,798
Time deposits	16,220	10,504
Credit balances of factoring clients	1,067	995
Securities sold under customer repurchase agreements	454	436
Other short-term debt		1,750
Long-term borrowings	39,011	4,330
Accrued interest payable	121	57
Fair value of derivative financial instruments	825	486
Estimate of Fair Value Measurement | Level 1
Financial Assets
Cash and due from banks	917	518
Interest earning deposits at banks	37,846	5,025
Securities purchased under agreements to resell	0
Investment in marketable equity securities	24	32
Investment securities available for sale	0	0
Investment securities held to maturity	0	0
Loans held for sale	0	0
Net loans	0	0
Accrued interest receivable	0	0
Federal Home Loan Bank stock	0	0
Mortgage servicing rights	0	0
Interest rate & other derivative — non-qualifying hedges	0	0
Financial Liabilities
Deposits with no stated maturity	0
Deposits with no stated maturity		0
Time deposits	0	0
Credit balances of factoring clients	0	0
Securities sold under customer repurchase agreements	0	0
Other short-term debt		0
Long-term borrowings	0	0
Accrued interest payable	0	0
Fair value of derivative financial instruments	0	0
Estimate of Fair Value Measurement | Level 2
Financial Assets
Cash and due from banks	0	0
Interest earning deposits at banks	0	0
Securities purchased under agreements to resell	298
Investment in marketable equity securities	52	63
Investment securities available for sale	11,743	8,821
Investment securities held to maturity	8,652	8,795
Loans held for sale	42	4
Net loans	1,552	1,679
Accrued interest receivable	732	329
Federal Home Loan Bank stock	119	197
Mortgage servicing rights	0	0
Interest rate & other derivative — non-qualifying hedges	755	159
Financial Liabilities
Deposits with no stated maturity	124,894
Deposits with no stated maturity		78,798
Time deposits	16,220	10,504
Credit balances of factoring clients	0	0
Securities sold under customer repurchase agreements	454	436
Other short-term debt		1,750
Long-term borrowings	39,011	4,312
Accrued interest payable	121	57
Fair value of derivative financial instruments	824	486
Estimate of Fair Value Measurement | Level 3
Financial Assets
Cash and due from banks	0	0
Interest earning deposits at banks	0	0
Securities purchased under agreements to resell	0
Investment in marketable equity securities	0	0
Investment securities available for sale	151	174
Investment securities held to maturity	0	0
Loans held for sale	73	45
Net loans	125,261	62,633
Accrued interest receivable	0	0
Federal Home Loan Bank stock	0	0
Mortgage servicing rights	47	47
Interest rate & other derivative — non-qualifying hedges	3	0
Financial Liabilities
Deposits with no stated maturity	0
Deposits with no stated maturity		0
Time deposits	0	0
Credit balances of factoring clients	1,067	995
Securities sold under customer repurchase agreements	0	0
Other short-term debt		0
Long-term borrowings	0	18
Accrued interest payable	0	0
Fair value of derivative financial instruments	$ 1	$ 0