Derivative Financial Instruments - Terminated Cash Flow and Fair Value Hedges (Details) - USD ($) $ in Millions |
9 Months Ended | 12 Months Ended |
|---|---|---|
Sep. 30, 2026 |
Dec. 31, 2025 |
|
| Derivative [Line Items] | ||
| Deferred gains recorded in AOCI | $ 308 | $ 335 |
| Swaps hedging commercial loans | ||
| Derivative [Line Items] | ||
| Net unrecognized after-tax gain (loss) on active hedges recorded in AOCI | $ (1,892) | $ (173) |
| Maximum length of time over which forecasted cash flows are hedged | 4 years | 5 years |
| Fair Value Hedges | ||
| Derivative [Line Items] | ||
| Net unrecognized pre-tax gain (loss) on terminated hedges | $ 22 | $ (56) |