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Investment Information - Net realized gains and losses (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2022 | Jun. 30, 2021 | Jun. 30, 2022 | Jun. 30, 2021
Available for sale securities: |  |  |  |  |
Available for sale securities, gross gains on investment sales |  | $ 15,186 | $ 115,541 | $ 34,893 | $ 180,543
Available for sale securities, gross losses on investment sales |  | (57,176) | (50,627) | (165,523) | (113,625)
Equity securities, at fair value: |  |  |  |  |
Net realized gains (losses) on sales during the period |  | 16,879 | 33,570 | 82,090 | 71,419
Net unrealized gains (losses) on equity securities still held at reporting date |  | (106,375) | 65,847 | (282,570) | 85,555
Allowance for credit losses: |  |  |  |  |
Allowance for credit losses - investments related |  | (25,026) | 896 | (56,748) | (752)
Allowance for credit losses - underwriting related |  | 842 | 1,381 | (3,444) | 6,649
Derivative instruments | [1] | (45,684) | (51,109) | (69,395) | (14,993)
Other |  | (128) | 10,224 | (3,537) | (12,821)
Net realized gains (losses) |  | (266,579) | 202,907 | (558,993) | 345,368
Fixed maturities |  |  |  |  |
Available for sale securities: |  |  |  |  |
Change in fair value of assets and liabilities accounted for using the fair value option |  | (39,255) | 10,912 | (69,844) | 27,465
Other investments |  |  |  |  |
Available for sale securities: |  |  |  |  |
Change in fair value of assets and liabilities accounted for using the fair value option |  | (21,710) | 60,884 | (17,321) | 107,739
Equity securities |  |  |  |  |
Available for sale securities: |  |  |  |  |
Change in fair value of assets and liabilities accounted for using the fair value option |  | (2,124) | 5,492 | (5,437) | 7,557
Short-term investments |  |  |  |  |
Available for sale securities: |  |  |  |  |
Change in fair value of assets and liabilities accounted for using the fair value option |  | $ (2,008) | $ (104) | $ (2,157) | $ 632
[1] | See note 9 for information on the Company’s derivative instruments.

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