Fair Value Measurements, Gains (Losses) on Changes in Fair Value Included in Earnings (Details) - Fair value option election [Member] - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Trading asset [Member] \| Mortgage banking noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	$ 0	$ 0
Trading asset [Member] \| Net gains from trading and securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	(53)	(3)
Trading asset [Member] \| Other noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Other assets [Member] \| Mortgage banking noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	21
Other assets [Member] \| Net gains from trading and securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Other assets [Member] \| Other noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Other liabilities [Member] \| Mortgage banking noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Other liabilities [Member] \| Net gains from trading and securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Other liabilities [Member] \| Other noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	(6)	3
Long-term debt [Member] \| Mortgage banking noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	0	0
Long-term debt [Member] \| Net gains from trading and securities [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	99	(26)
Long-term debt [Member] \| Other noninterest income [Member]
Fair Value, Option, Quantitative Disclosures [Line Items]
Fair value option, changes in fair value, gain (loss)	$ 0	$ 0