Fair Value Measurements (Reconciliation of Net Beginning and Ending Balances Recorded for Net Assets and Liabilities Classified as Level 3) (Detail) - USD ($) $ in Millions |
3 Months Ended | 9 Months Ended | ||||
|---|---|---|---|---|---|---|
Sep. 30, 2026 |
Sep. 30, 2025 |
Sep. 30, 2026 |
Sep. 30, 2025 |
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| Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] | ||||||
| Beginning balance | $ 289 | $ 55 | $ 277 | $ 58 | ||
| Unrealized and realized (gain)/loss included in net income(b) | [1] | 15 | (2) | 32 | 1 | |
| Settlements of derivative instruments | (4) | (2) | (9) | (8) | ||
| Ending balance | $ 300 | $ 285 | $ 300 | $ 285 | ||
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