Fair Value Option - Aggregate Differences (Details) - USD ($)	Sep. 30, 2025	Dec. 31, 2024
Long-term beneficial interests
Performing loans, ninety days or more past due	$ 0	$ 0
Lending-related commitments, fair value option elected
Long-term beneficial interests
Contractual amount of lending-related commitments	19,500,000,000	12,200,000,000
Contractual lending-related commitments, fair value	(2,000,000)	50,000,000
Contractual principal outstanding
Loans
Nonaccrual loans	4,889,000,000	5,140,000,000
All other performing loans	67,735,000,000	52,513,000,000
Total loans	72,747,000,000	57,703,000,000
Contractual principal outstanding | Principal-protected debt
Long-term debt
Total long-term debt	70,964,000,000	57,414,000,000
Contractual principal outstanding | Loans reported as trading assets
Loans
Nonaccrual loans	3,306,000,000	3,429,000,000
All other performing loans	14,138,000,000	12,171,000,000
Contractual principal outstanding | Loans
Loans
Nonaccrual loans	1,583,000,000	1,711,000,000
90 or more days past due and government guaranteed	123,000,000	50,000,000
All other performing loans	53,597,000,000	40,342,000,000
Fair value
Loans
Nonaccrual loans	1,913,000,000	1,956,000,000
All other performing loans	65,882,000,000	50,665,000,000
Total loans	67,914,000,000	52,666,000,000
Long-term debt
Total long-term debt	124,178,000,000	100,780,000,000
Long-term beneficial interests
Total long-term beneficial interests	8,000,000	1,000,000
Fair value | Principal-protected debt
Long-term debt
Total long-term debt	61,024,000,000	47,780,000,000
Fair value | Nonprincipal-protected debt
Long-term debt
Total long-term debt	63,154,000,000	53,000,000,000
Long-term beneficial interests
Total long-term beneficial interests	8,000,000	1,000,000
Fair value | Loans reported as trading assets
Loans
Nonaccrual loans	608,000,000	464,000,000
All other performing loans	12,620,000,000	10,852,000,000
Fair value | Loans
Loans
Nonaccrual loans	1,305,000,000	1,492,000,000
90 or more days past due and government guaranteed	119,000,000	45,000,000
All other performing loans	53,262,000,000	39,813,000,000
Fair value over/(under) contractual principal outstanding
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	(2,976,000,000)	(3,184,000,000)
All other performing loans	(1,853,000,000)	(1,848,000,000)
Total loans	(4,833,000,000)	(5,037,000,000)
Fair value over/(under) contractual principal outstanding | Principal-protected debt
Long-term debt
Long-term debt, Fair value over/(under) contractual principal outstanding	(9,940,000,000)	(9,634,000,000)
Fair value over/(under) contractual principal outstanding | Loans reported as trading assets
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	(2,698,000,000)	(2,965,000,000)
All other performing loans	(1,518,000,000)	(1,319,000,000)
Fair value over/(under) contractual principal outstanding | Loans
Loans
Nonaccrual loans, Fair value over/(under) contractual principal outstanding	(278,000,000)	(219,000,000)
90 or more days past due and government guaranteed, Fair value over/(under) contractual principal outstanding	(4,000,000)	(5,000,000)
All other performing loans	$ (335,000,000)	$ (529,000,000)