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Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands | Mar. 31, 2022 USD ($) position | Dec. 31, 2021 USD ($)
--- | --- | ---
Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | $ 4,186,326 | $ 2,633,955
Gross Unrealized Loss | 180,531 | 32,410
State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 1,455,908 | 531,880
Gross Unrealized Loss | 60,924 | 9,559
Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 1,210,459 | 664,881
Gross Unrealized Loss | 64,409 | 11,662
Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 4,085,270 | 3,908,329
Gross Unrealized Loss | $ 63,573 | $ 18,794
Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 58 |
Aggregate Fair Value | $ 177,782 |
Gross Unrealized Loss | $ 35,386 |
Noninvestment Grade Investments at Loss Position | Foreign government |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 37 |
Aggregate Fair Value | $ 132,306 |
Gross Unrealized Loss | $ 30,753 |
Noninvestment Grade Investments at Loss Position | Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 12 |
Aggregate Fair Value | $ 30,071 |
Gross Unrealized Loss | $ 3,158 |
Noninvestment Grade Investments at Loss Position | State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 13,583 |
Gross Unrealized Loss | $ 1,422 |
Noninvestment Grade Investments at Loss Position | Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 7 |
Aggregate Fair Value | $ 1,785 |
Gross Unrealized Loss | $ 48 |
Noninvestment Grade Investments at Loss Position | Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 37 |
Gross Unrealized Loss | $ 5 |

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