Loss and Loss Adjustment Expense Reserves (Schedule of Loss and Loss Adjustment Expenses Reserves) (Detail) - USD ($) $ in Millions |
3 Months Ended | |||||
|---|---|---|---|---|---|---|
Mar. 31, 2023 |
Mar. 31, 2022 |
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| Loss And Loss Adjustment Expense Reserves [Line Items] | ||||||
| Changes in unearned premium revenue | $ 9 | $ 15 | ||||
| Loss And Lae Reserves [Member] | ||||||
| Loss And Loss Adjustment Expense Reserves [Line Items] | ||||||
| Gross loss and LAE reserve, beginning balance | [1] | 439 | ||||
| Loss payments for cases | (28) | |||||
| Accretion of claim liability discount | 4 | |||||
| Changes in discount rates | 11 | |||||
| Changes in assumptions | [2] | (47) | ||||
| Changes in unearned premium revenue | 0 | |||||
| Gross loss and LAE reserve, ending balance | [1] | $ 379 | ||||
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