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Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands | Mar. 31, 2023 USD ($) position | Dec. 31, 2022 USD ($)
--- | --- | ---
Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | $ 5,869,295 | $ 6,040,137
Gross Unrealized Loss | 340,440 | 406,746
State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 2,079,792 | 2,319,240
Gross Unrealized Loss | 127,420 | 168,592
Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 1,632,585 | 1,572,867
Gross Unrealized Loss | 166,440 | 190,958
Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 3,406,951 | 3,746,285
Gross Unrealized Loss | $ 117,853 | $ 152,322
Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 65 |
Aggregate Fair Value | $ 167,130 |
Gross Unrealized Loss | $ 71,448 |
Noninvestment Grade Investments at Loss Position | Foreign government |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 33 |
Aggregate Fair Value | $ 105,347 |
Gross Unrealized Loss | $ 64,516 |
Noninvestment Grade Investments at Loss Position | Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 16 |
Aggregate Fair Value | $ 45,507 |
Gross Unrealized Loss | $ 3,789 |
Noninvestment Grade Investments at Loss Position | State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 12,066 |
Gross Unrealized Loss | $ 2,936 |
Noninvestment Grade Investments at Loss Position | Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 14 |
Aggregate Fair Value | $ 4,202 |
Gross Unrealized Loss | $ 199 |
Noninvestment Grade Investments at Loss Position | Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 8 |
Gross Unrealized Loss | $ 8 |

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