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Investments (Net Realized and Unrealized Investment Gains and (Losses)) (Details) - USD ($) $ in Thousands | 3 Months Ended
--- | ---
Mar. 31, 2023 | Mar. 31, 2022
Gain (Loss) on Securities [Line Items] |  |
Gross gains on sales | $ 3,784 | $ 2,197
Gross losses on sales | (12,930) | (13,560)
Net realized (losses) gains on disposals | (9,146) | (11,363)
Net unrealized gains (losses) on equity securities | 3,248 | (2,154)
Losses on securities for which we have the intent to sell | (304) | (4,797)
Net realized and unrealized investment gains (losses) | 3,344 | (40,352)
Change in net realized and unrealized investment gains | 43,700 |
Available-for-sale Securities [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Net credit loss (expense) benefit on fixed income securities | 9,529 | (22,052)
Held-to-maturity Securities [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Net credit loss (expense) benefit on fixed income securities | 0 | 14
Commercial Mortgage Loans [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Net credit loss (expense) benefit on fixed income securities | $ 17 | $ 0

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