Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2024	Jan. 01, 2024	Dec. 31, 2023
Change in Accounting Estimate [Line Items]
Debt Securities, Available-for-Sale, Accrued Interest, after Allowance for Credit Loss, Statement of Financial Position [Extensible Enumeration]	Other assets		Other assets
Past due threshold period for nonaccrual status	90 days
Retained earnings	$ 4,382		$ 3,964
Commercial
Change in Accounting Estimate [Line Items]
Financing Receivable, Excluding Accrued Interest, Charge-Off Past Due Threshold	180 days
Credit card and other
Change in Accounting Estimate [Line Items]
Financing Receivable, Excluding Accrued Interest, Charge-Off Past Due Threshold	120 days
Consumer | Other Non-Real Estate Consumer Loans
Change in Accounting Estimate [Line Items]
Financing Receivable, Excluding Accrued Interest, Charge-Off Past Due Threshold	120 days
Accounting Standards Update 2023-02
Change in Accounting Estimate [Line Items]
Retained earnings		$ 8
Deposit Bases
Change in Accounting Estimate [Line Items]
Intangible assets, amortization period	10 years
Minimum | Furniture and Fixtures
Change in Accounting Estimate [Line Items]
Useful life of premises and equipment	3 years
Minimum | Building
Change in Accounting Estimate [Line Items]
Useful life of premises and equipment	7 years
Maximum | Furniture and Fixtures
Change in Accounting Estimate [Line Items]
Useful life of premises and equipment	15 years
Maximum | Building
Change in Accounting Estimate [Line Items]
Useful life of premises and equipment	45 years
Non-Accruing
Change in Accounting Estimate [Line Items]
Accounts receivable, net	$ 14		$ 13