Loans and Related Allowance for Credit Losses (Narrative) (Details) $ in Millions	Mar. 31, 2025 USD ($) portfolio_segment	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)
Financing Receivable, Credit Quality Indicator [Line Items]
Number of portfolio segments \| portfolio_segment	2
Financing receivable, after allowance for credit loss	$ 314,306	$ 311,981
Allowance for credit loss	5,218	5,200	$ 5,365
Federal Reserve Bank \| Asset Pledged as Collateral without Right
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance for credit loss	44,500	43,400
Federal Home Loan Bank \| Asset Pledged as Collateral without Right
Financing Receivable, Credit Quality Indicator [Line Items]
Financing receivable, after allowance for credit loss	$ 84,900	$ 89,000

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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