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Fair Value Measurements (Tables) | 12 Months Ended
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Dec. 31, 2024
Fair Value Disclosures [Abstract] |
Assets And Liabilities Measured At Fair value, On A Recurring Basis | The following tables present the assets and liabilities measured at fair value as of December 31, 2024 and 2023 by level:
(In thousands) | Total |  | Level 1 |  | Level 2 |  | Level 3
December 31, 2024 |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |
Fixed maturity securities available for sale: |  |  |  |  |  |  |
U.S. government and government agency | $ | 2,235,341 |  |  | $ | — |  |  | $ | 2,235,341 |  |  | $ | — |
State and municipal | 2,294,644 |  |  | — |  |  | 2,294,644 |  |  | — |
Mortgage-backed securities | 3,765,490 |  |  | — |  |  | 3,765,490 |  |  | — |
Asset-backed securities | 3,885,012 |  |  | — |  |  | 3,885,012 |  |  | — |
Corporate | 8,417,641 |  |  | — |  |  | 8,397,974 |  |  | 19,667 |
Foreign government | 1,755,325 |  |  | — |  |  | 1,755,325 |  |  | — |
Total fixed maturity securities available for sale | 22,353,453 |  |  | — |  |  | 22,333,786 |  |  | 19,667 |
Equity securities: |  |  |  |  |  |  |
Common stocks | 760,167 |  |  | 757,115 |  |  | 1,011 |  |  | 2,041 |
Preferred stocks | 443,621 |  |  | — |  |  | 439,947 |  |  | 3,674 |
Total equity securities | 1,203,788 |  |  | 757,115 |  |  | 440,958 |  |  | 5,715 |
Arbitrage trading account | 1,122,599 |  |  | 1,062,459 |  |  | 56,630 |  |  | 3,510 |
Total | $ | 24,679,840 |  |  | $ | 1,819,574 |  |  | $ | 22,831,374 |  |  | $ | 28,892 |
Liabilities: |  |  |  |  |  |  |
Trading account securities sold but not yet purchased | $ | 73,358 |  |  | $ | 73,358 |  |  | $ | — |  |  | $ | — |
December 31, 2023 |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |
Fixed maturity securities available for sale: |  |  |  |  |  |  |
U.S. government and government agency | $ | 1,716,731 |  |  | $ | — |  |  | $ | 1,716,731 |  |  | $ | — |
State and municipal | 2,634,422 |  |  | — |  |  | 2,634,422 |  |  | — |
Mortgage-backed securities | 2,266,455 |  |  | — |  |  | 2,266,455 |  |  | — |
Asset-backed securities | 4,187,040 |  |  | — |  |  | 4,187,040 |  |  | — |
Corporate | 7,654,059 |  |  | — |  |  | 7,654,059 |  |  | — |
Foreign government | 1,666,229 |  |  | — |  |  | 1,666,229 |  |  | — |
Total fixed maturity securities available for sale | 20,124,936 |  |  | — |  |  | 20,124,936 |  |  | — |
Equity securities: |  |  |  |  |  |  |
Common stocks | 838,054 |  |  | 835,338 |  |  | 1,158 |  |  | 1,558 |
Preferred stocks | 252,293 |  |  | — |  |  | 248,598 |  |  | 3,695 |
Total equity securities | 1,090,347 |  |  | 835,338 |  |  | 249,756 |  |  | 5,253 |
Arbitrage trading account | 938,049 |  |  | 546,110 |  |  | 388,167 |  |  | 3,772 |
Total | $ | 22,153,332 |  |  | $ | 1,381,448 |  |  | $ | 20,762,859 |  |  | $ | 9,025 |
Liabilities: |  |  |  |  |  |  |
Trading account securities sold but not yet purchased | $ | 9,357 |  |  | $ | 9,357 |  |  | $ | — |  |  | $ | — |
Summarize Changes In Level 3 Assets and Liabilities | The following tables summarize changes in Level 3 assets and liabilities for the years ended December 31, 2024 and 2023:
| Gains (Losses) Included in:
(In thousands) | Beginning Balance |  | Earnings (Losses) |  | Other Comprehensive Losses |  | Impairments |  | Purchases |  | Sales |  | Paydowns/Maturities |  | Transfers In / Out |  |  |  |  | Ending Balance
Year ended December 31, 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed maturity securities available for sale: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate | $ | — |  |  | $ | — |  |  | $ | (333) |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 20,000 |  |  |  |  |  | $ | 19,667 |
Total | — |  |  | — |  |  | (333) |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 20,000 |  |  |  |  |  | 19,667 |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stocks | 1,558 |  |  | 611 |  |  | — |  |  | — |  |  | — |  |  | (128) |  |  | — |  |  | — |  |  |  |  |  | 2,041 |
Preferred stocks | 3,695 |  |  | 36 |  |  | — |  |  | — |  |  | — |  |  | (57) |  |  | — |  |  | — |  |  |  |  |  | 3,674 |
Total | 5,253 |  |  | 647 |  |  | — |  |  | — |  |  | — |  |  | (185) |  |  | — |  |  | — |  |  |  |  |  | 5,715 |
Arbitrage trading account | 3,772 |  |  | (261) |  |  | — |  |  | — |  |  | — |  |  | (38) |  |  | — |  |  | 37 |  |  |  |  |  | 3,510 |
Total | $ | 9,025 |  |  | $ | 386 |  |  | $ | (333) |  |  | $ | — |  |  | $ | — |  |  | $ | (223) |  |  | $ | — |  |  | $ | 20,037 |  |  |  |  |  | $ | 28,892 |
Year ended December 31, 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Fixed maturity securities available for sale: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Corporate | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  |  |  |  | $ | — |
Total | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  |  |  |  | — |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stocks | 2,599 |  |  | (1,041) |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  |  |  |  | 1,558 |
Preferred stocks | 11,299 |  |  | (3) |  |  | — |  |  | (7,601) |  |  | — |  |  |  |  | — |  |  | — |  |  |  |  |  | 3,695 |
Total | 13,898 |  |  | (1,044) |  |  | — |  |  | (7,601) |  |  | — |  |  | — |  |  | — |  |  | — |  |  |  |  |  | 5,253 |
Arbitrage trading account | 3,590 |  |  | 117 |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 65 |  |  |  |  |  | 3,772 |
Total | $ | 17,488 |  |  | $ | (927) |  |  | $ | — |  |  | $ | (7,601) |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 65 |  |  |  |  |  | $ | 9,025 |

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- Definition Tabular disclosure of assets and liabilities, including [financial] instruments measured at fair value that are classified in stockholders' equity, if any, that are measured at fair value on a recurring basis. The disclosures contemplated herein include the fair value measurements at the reporting date by the level within the fair value hierarchy in which the fair value measurements in their entirety fall, segregating fair value measurements using quoted prices in active markets for identical assets (Level 1), significant other observable inputs (Level 2), and significant unobservable inputs (Level 3). + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (b) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef -Topic 820 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org/1943274/2147482106/820-10-50-2 + Details
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