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Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands | Jun. 30, 2023 USD ($) position | Dec. 31, 2022 USD ($)
--- | --- | ---
Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 59 |
Aggregate Fair Value | $ 143,076 |
Gross Unrealized Loss | $ 82,888 |
Foreign government | Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 28 |
Aggregate Fair Value | $ 104,753 |
Gross Unrealized Loss | 76,573 |
Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 6,363,534 | $ 6,040,137
Gross Unrealized Loss | $ 378,384 | 406,746
Corporate | Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 14 |
Aggregate Fair Value | $ 25,942 |
Gross Unrealized Loss | 4,052 |
State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 2,210,995 | 2,319,240
Gross Unrealized Loss | $ 144,995 | 168,592
State and municipal | Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 7,971 |
Gross Unrealized Loss | 2,031 |
Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 1,752,868 | 1,572,867
Gross Unrealized Loss | $ 190,029 | 190,958
Mortgage-backed | Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 14 |
Aggregate Fair Value | $ 4,393 |
Gross Unrealized Loss | 226 |
Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 3,406,690 | 3,746,285
Gross Unrealized Loss | $ 116,036 | $ 152,322
Asset-backed | Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 2 |
Aggregate Fair Value | $ 17 |
Gross Unrealized Loss | $ 6 |

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