Fair Value - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Mar. 31, 2023	Dec. 31, 2022
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 9,061	$ 8,995
Marketable equity securities	85	95
Interest rate & other derivative — non-qualifying hedges	547	159
Fair value of derivative financial instruments	791	486
U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,978	1,898
Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	4,848	4,795
Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,585	1,604
Fair Value, Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	9,061	8,995
Marketable equity securities	85	95
Loans held for sale	9	4
Interest rate & other derivative — non-qualifying hedges	547	159
Fair value of derivative financial instruments	791	486
Fair Value, Recurring | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	285	158
Fair value of derivative financial instruments	535	482
Fair Value, Recurring | Foreign currency forward contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	262	1
Fair value of derivative financial instruments	255	4
Fair Value, Recurring | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	1	0
Fair Value, Recurring | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Marketable equity securities	29	32
Loans held for sale	0	0
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 1 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 1 | Foreign currency forward contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 1 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	8,901	8,821
Marketable equity securities	56	63
Loans held for sale	9	4
Interest rate & other derivative — non-qualifying hedges	546	159
Fair value of derivative financial instruments	790	486
Fair Value, Recurring | Level 2 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	284	158
Fair value of derivative financial instruments	535	482
Fair Value, Recurring | Level 2 | Foreign currency forward contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	262	1
Fair value of derivative financial instruments	255	4
Fair Value, Recurring | Level 2 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	160	174
Marketable equity securities	0	0
Loans held for sale	0	0
Interest rate & other derivative — non-qualifying hedges	1	0
Fair value of derivative financial instruments	1	0
Fair Value, Recurring | Level 3 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	1	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 3 | Foreign currency forward contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	0	0
Fair Value, Recurring | Level 3 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Interest rate & other derivative — non-qualifying hedges	0	0
Fair value of derivative financial instruments	1	0
Fair Value, Recurring | U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,978	1,898
Fair Value, Recurring | U.S. Treasury | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | U.S. Treasury | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,978	1,898
Fair Value, Recurring | U.S. Treasury | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Government agency
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	150	162
Fair Value, Recurring | Government agency | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Government agency | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	150	162
Fair Value, Recurring | Government agency | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	4,848	4,795
Fair Value, Recurring | Residential mortgage-backed securities | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Residential mortgage-backed securities | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	4,848	4,795
Fair Value, Recurring | Residential mortgage-backed securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,585	1,604
Fair Value, Recurring | Commercial mortgage-backed securities | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Commercial mortgage-backed securities | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,585	1,604
Fair Value, Recurring | Commercial mortgage-backed securities | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Corporate bonds
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	500	536
Fair Value, Recurring | Corporate bonds | Level 1
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	0	0
Fair Value, Recurring | Corporate bonds | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	340	362
Fair Value, Recurring | Corporate bonds | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 160	$ 174