Derivatives - Gains and Losses on Derivatives and Hedged Items Designated in Fair Value Hedges (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2026	Mar. 31, 2025
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	$ 579	$ (2,050)
Hedged Item	(606)	1,997
Interest rate risk on long-term debt
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	(994)	2,476
Hedged Item	1,008	(2,480)
Interest rate and foreign currency risk
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	79	(202)
Hedged Item	(82)	202
Interest rate and foreign currency risk \| Interest Income
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	2	9
Interest rate and foreign currency risk \| Market making and similar activities
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	81	(210)
Interest rate risk on available-for-sale securities
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	1,381	(3,227)
Hedged Item	(1,419)	3,178
Price risk on commodity inventory \| Interest Income
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	113	(1,097)
Hedged Item	(113)	1,097
Accumulated Other Comprehensive Income (Loss) \| Interest rate and foreign currency risk
Effect of Fair Value Hedges on Results of Operations [Abstract]
Derivative	$ (4)	$ (1)