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Investments (Net Realized and Unrealized Investment Gains and (Losses)) (Details) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Gain (Loss) on Securities [Line Items] |  |  |  |
Gross gains on sales | $ 367 | $ 7,094 | $ 5,307 | $ 23,843
Gross losses on sales | (5,264) | (19,668) | (30,146) | (52,573)
Net realized gains (losses) on disposals | (4,897) | (12,574) | (24,839) | (28,730)
Net unrealized gains (losses) on equity securities | 489 | (7,777) | 8,662 | (31,791)
Losses on securities for which we have the intent to sell | 0 | (913) | (645) | (6,412)
Net realized and unrealized investment gains (losses) | (6,880) | (25,681) | (8,962) | (108,913)
Available-for-sale Securities [Member] |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |
Net credit loss benefit (expense) | (2,468) | (4,471) | 7,925 | (42,042)
Held-to-maturity Securities [Member] |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |
Net credit loss benefit (expense) | 0 | 54 | 0 | 62
Commercial Mortgage Loans [Member] |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |
Net credit loss benefit (expense) | $ (4) | $ 0 | $ (65) | $ 0

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