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v3.20.4

Reserve for Loss and Loss Expense (Reconciliation of Claims Development to Liability) (Details) - USD ($) $ in Thousands | Dec. 31, 2020 | Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | --- | --- | ---
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | $ 3,576,212 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 554,269 | $ 544,162 | $ 537,388 | $ 585,855
Unallocated loss expenses | 129,874 |  |  |
Gross liability for unpaid loss and loss expenses | 4,260,355 | $ 4,067,163 | $ 3,893,868 | $ 3,771,240
Standard Commercial Lines [Member] | General Liability [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 1,380,902 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 215,136 |  |  |
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 828,146 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 210,450 |  |  |
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 630,512 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 11,611 |  |  |
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 91,419 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 6,849 |  |  |
Standard Commercial Lines [Member] | Commercial Property [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 74,182 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 21,760 |  |  |
Standard Commercial Lines [Member] | Other Commercial [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 16,359 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 2,853 |  |  |
Standard Commercial Lines [Member] | Total Standard Commercial Lines [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 3,021,520 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 468,659 |  |  |
Standard Personal Lines | Personal Automobile [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 94,237 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 42,403 |  |  |
Standard Personal Lines | Homeowners [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 44,159 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 847 |  |  |
Standard Personal Lines | Other Personal [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 10,751 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 29,589 |  |  |
Standard Personal Lines | Standard Personal Lines |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 149,147 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 72,839 |  |  |
E&S Lines [Member] | General Liability [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 389,460 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 12,195 |  |  |
E&S Lines [Member] | Total E&S Lines [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 405,545 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | 12,771 |  |  |
E&S Lines [Member] | Standard Commercial Lines [Member] |  |  |  |
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items] |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 16,085 |  |  |
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments | $ 576 |  |  |

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