Investments - Narrative (Details) - USD ($) |
3 Months Ended | 12 Months Ended |
|---|---|---|
Mar. 31, 2024 |
Dec. 31, 2023 |
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| Investments, Debt and Equity Securities [Abstract] | ||
| Available-for-sale debt securities | $ 0 | $ 0 |
| Debt securities in an unrealized loss position | 1,100,000,000 | 777,000,000 |
| Debt securities, unrealized loss | 18,000,000 | 16,000,000 |
| Debt securities, available-for-sale, continuous unrealized loss position, 12 months or longer, accumulated loss | 479,000,000 | 283,000,000 |
| Debt securities, continuous unrealized loss position, 12 months or longer | $ 16,000,000 | $ 14,000,000 |
| X | ||||||||||
- Definition Amount excluding accrued interest, of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale). Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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| X | ||||||||||
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for more than 12 months, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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| X | ||||||||||
- Definition Amount of accumulated unrealized loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in continuous unrealized loss position for 12 months or longer, without allowance for credit loss. Includes beneficial interest in securitized financial asset. Reference 1: http://fasb.org/us-gaap/role/ref/otherTransitionRef
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| X | ||||||||||
- Definition Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), in unrealized loss position without allowance for credit loss. Reference 1: http://www.xbrl.org/2003/role/exampleRef
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| X | ||||||||||
- Definition Amount of unrealized gain (loss) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), investment in debt security measured at amortized cost (held-to-maturity) and investment in debt security measured at fair value with change in fair value recognized in net income (trading). Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
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- References No definition available.
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