Investments - Schedule of Available-For-Sale Securities in an Unrealized Loss Position (Details) - USD ($) |
12 Months Ended | |
|---|---|---|
Dec. 31, 2025 |
Dec. 31, 2024 |
|
| Fair value: | ||
| Less than 12 months | $ 8,238,000,000 | $ 32,706,000,000 |
| 12 months or longer | 14,135,000,000 | 21,095,000,000 |
| Total | 22,373,000,000 | 53,801,000,000 |
| Gross unrealized losses: | ||
| Less than 12 months | (14,000,000) | (399,000,000) |
| 12 months or longer | (484,000,000) | (983,000,000) |
| Total | (498,000,000) | (1,382,000,000) |
| Debt Securities, Available-for-Sale, Unrealized Gain (Loss) [Abstract] | ||
| Gross unrealized gain included in accumulated other comprehensive gain/(loss) | 626,000,000 | 0 |
| U.S. government obligations | ||
| Fair value: | ||
| Less than 12 months | 6,733,000,000 | 31,032,000,000 |
| 12 months or longer | 10,464,000,000 | 18,732,000,000 |
| Total | 17,197,000,000 | 49,764,000,000 |
| Gross unrealized losses: | ||
| Less than 12 months | (12,000,000) | (383,000,000) |
| 12 months or longer | (226,000,000) | (630,000,000) |
| Total | (238,000,000) | (1,013,000,000) |
| U.S. agency obligations | ||
| Fair value: | ||
| Less than 12 months | 706,000,000 | |
| 12 months or longer | 0 | |
| Total | 706,000,000 | |
| Gross unrealized losses: | ||
| Less than 12 months | (1,000,000) | |
| 12 months or longer | 0 | |
| Total | (1,000,000) | |
| Non-U.S. government obligations | ||
| Fair value: | ||
| Less than 12 months | 799,000,000 | 1,674,000,000 |
| 12 months or longer | 3,671,000,000 | 2,363,000,000 |
| Total | 4,470,000,000 | 4,037,000,000 |
| Gross unrealized losses: | ||
| Less than 12 months | (1,000,000) | (16,000,000) |
| 12 months or longer | (258,000,000) | (353,000,000) |
| Total | $ (259,000,000) | $ (369,000,000) |