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Fixed Maturity Securities In An Unrealized Loss Position (Non-Investment Grade Fixed Maturity Securities) (Details) $ in Thousands | Sep. 30, 2022 USD ($) position | Dec. 31, 2021 USD ($)
--- | --- | ---
Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | $ 6,060,101 | $ 2,633,955
Gross Unrealized Loss | 473,698 | 32,410
State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 2,426,386 | 531,880
Gross Unrealized Loss | 184,620 | 9,559
Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 1,539,162 | 664,881
Gross Unrealized Loss | 180,678 | 11,662
Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Aggregate Fair Value | 4,011,844 | 3,908,329
Gross Unrealized Loss | $ 161,474 | $ 18,794
Noninvestment Grade Investments at Loss Position |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 64 |
Aggregate Fair Value | $ 178,544 |
Gross Unrealized Loss | $ 68,717 |
Noninvestment Grade Investments at Loss Position | Foreign government |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 38 |
Aggregate Fair Value | $ 116,869 |
Gross Unrealized Loss | $ 58,770 |
Noninvestment Grade Investments at Loss Position | Corporate |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 12 |
Aggregate Fair Value | $ 46,657 |
Gross Unrealized Loss | $ 6,277 |
Noninvestment Grade Investments at Loss Position | State and municipal |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 1 |
Aggregate Fair Value | $ 11,582 |
Gross Unrealized Loss | $ 3,421 |
Noninvestment Grade Investments at Loss Position | Mortgage-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 11 |
Aggregate Fair Value | $ 3,398 |
Gross Unrealized Loss | $ 229 |
Noninvestment Grade Investments at Loss Position | Asset-backed |  |
Debt Securities, Available-for-sale [Line Items] |  |
Number of Securities | position | 2 |
Aggregate Fair Value | $ 38 |
Gross Unrealized Loss | $ 20 |

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