Fair Value of Assets and Liabilities - Changes in Fair Value of Assets and Liabilities which Fair Value Option Included in Current Period Earnings (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2025	Sep. 30, 2024	Sep. 30, 2025	Sep. 30, 2024
Mortgage banking noninterest income \| Loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Changes in fair value included in net income	$ 0	$ 0	$ 2	$ 1

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.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 820
-SubTopic 10
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 820
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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