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Fair Value Measurements (Tables) | 3 Months Ended
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Mar. 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 on a recurring basis as of March 31, 2024 and December 31, 2023 by level:
(In thousands) | Total |  | Level 1 |  | Level 2 |  | Level 3
March 31, 2024 |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |
Fixed maturity securities available for sale: |  |  |  |  |  |  |
U.S. government and government agency | $ | 1,829,552 |  |  | $ | — |  |  | $ | 1,829,552 |  |  | $ | — |
State and municipal | 2,552,786 |  |  | — |  |  | 2,552,786 |  |  | — |
Mortgage-backed | 2,408,018 |  |  | — |  |  | 2,408,018 |  |  | — |
Asset-backed | 4,239,561 |  |  | — |  |  | 4,239,561 |  |  | — |
Corporate | 8,162,703 |  |  | — |  |  | 8,162,703 |  |  | — |
Foreign government | 1,718,252 |  |  | — |  |  | 1,718,252 |  |  | — |
Total fixed maturity securities available for sale | 20,910,872 |  |  | — |  |  | 20,910,872 |  |  | — |
Equity securities: |  |  |  |  |  |  |
Common stocks | 846,669 |  |  | 843,441 |  |  | 1,059 |  |  | 2,169 |
Preferred stocks | 331,379 |  |  | — |  |  | 327,743 |  |  | 3,636 |
Total equity securities | 1,178,048 |  |  | 843,441 |  |  | 328,802 |  |  | 5,805 |
Arbitrage trading account | 1,146,119 |  |  | 752,159 |  |  | 390,284 |  |  | 3,676 |
Total | $ | 23,235,039 |  |  | $ | 1,595,600 |  |  | $ | 21,629,958 |  |  | $ | 9,481 |
Liabilities: |  |  |  |  |  |  |
Trading account securities sold but not yet purchased | $ | 40,298 |  |  | $ | 40,298 |  |  | $ | — |  |  | $ | — |
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 | 2,266,455 |  |  | — |  |  | 2,266,455 |  |  | — |
Asset-backed | 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 | The following tables summarize changes in Level 3 assets and liabilities for the three months ended March 31, 2024 and for the year ended December 31, 2023:
Gains (Losses) Included In:
(In thousands) | Beginning Balance |  | Earnings (Losses) |  | Other Comprehensive Income (Losses) |  | Impairments |  | Purchases |  | Sales |  | Paydowns / Maturities |  | Transfers In / (Out) |  | Ending Balance
Three Months Ended March 31, 2024 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Equity securities: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Common stocks | $ | 1,558 |  |  | $ | 611 |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | 2,169 |
Preferred stocks | 3,695 |  |  | (2) |  |  | — |  |  | — |  |  | — |  |  | (57) |  |  | — |  |  | — |  |  | 3,636 |
Total | 5,253 |  |  | 609 |  |  | — |  |  | — |  |  | — |  |  | (57) |  |  | — |  |  | — |  |  | 5,805 |
Arbitrage trading account | 3,772 |  |  | (133) |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | 37 |  |  | 3,676 |
Total | $ | 9,025 |  |  | $ | 476 |  |  | $ | — |  |  | $ | — |  |  | $ | — |  |  | $ | (57) |  |  | $ | — |  |  | $ | 37 |  |  | $ | 9,481 |
Year Ended December 31, 2023 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Assets: |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
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 financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Section 50 -Paragraph 2C -SubTopic 10 -Topic 820 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2C Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (a) -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-2 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 820 -SubTopic 10 -Section 50 -Paragraph 3 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482106/820-10-50-3 Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef -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 + Details
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- Definition Fair Value, Assets and Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] + References No definition available. + Details
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