Fair Value - Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2022	Dec. 31, 2021
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 9,088	$ 9,203
Marketable equity securities	92	98
Fair value of derivative financial instruments	149	3
Fair value of derivative financial instruments	500	1
U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,900	2,005
Residential mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	4,784	4,729
Commercial mortgage-backed securities
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,673	1,640
Fair Value, Recurring
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	9,088	9,203
Marketable equity securities	92	98
Loans held for sale	7	99
Fair value of derivative financial instruments	149
Fair value of derivative financial instruments	500
Fair Value, Recurring | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	143
Fair value of derivative financial instruments	500
Fair Value, Recurring | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	6
Fair value of derivative financial instruments	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	30	34
Loans held for sale	0	0
Fair value of derivative financial instruments	0
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 1 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	0
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 1 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	0
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 2
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	8,912	8,996
Marketable equity securities	62	64
Loans held for sale	7	99
Fair value of derivative financial instruments	148
Fair value of derivative financial instruments	500
Fair Value, Recurring | Level 2 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	142
Fair value of derivative financial instruments	500
Fair Value, Recurring | Level 2 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	6
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	176	207
Marketable equity securities	0	0
Loans held for sale	0	0
Fair value of derivative financial instruments	1
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 3 | Interest rate contracts
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	1
Fair value of derivative financial instruments	0
Fair Value, Recurring | Level 3 | Other derivative
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Fair value of derivative financial instruments	0
Fair value of derivative financial instruments	0
Fair Value, Recurring | U.S. Treasury
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	1,900	2,005
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	1,900	2,005
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	173	221
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	173	221
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	4,784	4,729
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	4,784	4,729
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	1,673	1,640
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	1,673	1,640
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	558	608
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	382	401
Fair Value, Recurring | Corporate bonds | Level 3
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Investment securities available for sale	$ 176	$ 207