Fair Value Measurements - Schedule of Quantitative Information about Level 3 Fair Value Measurements (Details) $ in Millions	Jun. 30, 2024 USD ($)	Dec. 31, 2023 USD ($)
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets	$ 230	$ 181
Mortgage servicing assets excluded from OREO	12	8
Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets	230	181
Nonrecurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans	114	104
Level 3 | Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets	(1)	0
Insignificant level 3 assets, net of liabilities	3	4
Level 3 | Nonrecurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans	114	104
Market comparable pricing | Level 3 | Recurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, net of unearned income (residential)	$ 11	$ 9
Market comparable pricing | Level 3 | Recurring | Comparability factor | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, net of unearned income (residential), measurement input	0.6470	0.6267
Market comparable pricing | Level 3 | Recurring | Comparability factor | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, net of unearned income (residential), measurement input	0.9500	0.8960
Market comparable pricing | Level 3 | Recurring | Comparability factor | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Loans, net of unearned income (residential), measurement input	0.7525	0.7083
Discounted cash flow | Level 3 | Recurring | Interest rate
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets	$ (2)	$ 2
Discounted cash flow | Level 3 | Recurring | Interest rate | Probability of default | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	0.0002	0.0002
Discounted cash flow | Level 3 | Recurring | Interest rate | Probability of default | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	1	1
Discounted cash flow | Level 3 | Recurring | Interest rate | Probability of default | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	0.0450	0.0530
Discounted cash flow | Level 3 | Recurring | Interest rate | Loss given default | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	0	0
Discounted cash flow | Level 3 | Recurring | Interest rate | Loss given default | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	1	1
Discounted cash flow | Level 3 | Recurring | Interest rate | Loss given default | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Derivative assets, measurement input	0.500	0.477
Fair value of collateral | Level 3 | Nonrecurring
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans	$ 114	$ 104
Fair value of collateral | Level 3 | Nonrecurring | Credit and liquidity discount | Minimum
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans, measurement input	0	0
Fair value of collateral | Level 3 | Nonrecurring | Credit and liquidity discount | Maximum
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans, measurement input	0.9000	0.1000
Fair value of collateral | Level 3 | Nonrecurring | Credit and liquidity discount | Weighted Average
Fair Value, Option, Quantitative Disclosures [Line Items]
Collateral-dependent loans, measurement input	0.2300	0.0500
Appraised value | Level 3 | Nonrecurring
Fair Value, Option, Quantitative Disclosures [Line Items]
OREO and other Level 3 assets	$ 20	$ 21