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v3.23.2

Business Segments (Net Premiums Earned By Major Line of Business) (Details) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2023 | Jun. 30, 2022 | Jun. 30, 2023 | Jun. 30, 2022
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | $ 2,552,727 | $ 2,357,158 | $ 5,044,159 | $ 4,606,244
Insurance |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned |  | 2,070,157 |  | 4,032,991
Insurance | Operating Segments |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 2,246,394 | 2,070,157 | 4,428,269 | 4,032,991
Insurance | Other liability |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 893,629 | 789,363 | 1,750,778 | 1,538,754
Insurance | Short-tail lines |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 462,554 | 401,768 | 893,057 | 776,980
Insurance | Commercial automobile |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 318,421 | 301,741 | 629,843 | 583,975
Insurance | Workers' compensation |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 299,149 | 299,645 | 604,710 | 585,067
Insurance | Professional liability |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 272,641 | 277,640 | 549,881 | 548,215
Reinsurance & Monoline Excess |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned |  | 287,001 |  | 573,253
Reinsurance & Monoline Excess | Operating Segments |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 306,333 | 287,001 | 615,890 | 573,253
Reinsurance & Monoline Excess | Casualty reinsurance |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 188,860 | 190,659 | 382,590 | 374,781
Reinsurance & Monoline Excess | Monoline excess |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | 58,845 | 54,611 | 117,489 | 106,507
Reinsurance & Monoline Excess | Property reinsurance |  |  |  |
Revenue from External Customer [Line Items] |  |  |  |
Net premiums earned | $ 58,628 | $ 41,731 | $ 115,811 | $ 91,965

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