| Fiscal period | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | 2019 | 2018 | 2017 | 2016 |
| Period End Date | 12/31/2025 | 12/31/2024 | 12/31/2023 | 12/31/2022 | 12/31/2021 | 12/31/2020 | 12/31/2019 | 12/31/2018 | 12/31/2017 | 12/31/2016 |
| Earned premiums | 9,983.00 | 8,889.00 | 7,958.00 | 7,219.00 | 6,482.00 | 5,980.00 | 5,604.00 | 5,170.00 | 4,954.00 | 4,710.00 |
| Earned premiums:Property casualty | 9,653.00 | 8,568.00 | 7,645.00 | 6,924.00 | 6,184.00 | 5,691.00 | 5,334.00 | 4,920.00 | 4,722.00 | 4,482.00 |
| Earned premiums:Life | 330.00 | 321.00 | 313.00 | 295.00 | 298.00 | 289.00 | 270.00 | 250.00 | 232.00 | 228.00 |
| Earned premiums:Accident health | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Consolidated eliminations | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Realized investment gains and losses | 1,442.00 | 1,391.00 | 1,127.00 | (1,467.00) | 2,409.00 | 865.00 | 1,650.00 | (402.00) | 148.00 | 124.00 |
| Other | 27.00 | 25.00 | 25.00 | 11.00 | 5.00 | 8.00 | 12.00 | 5.00 | 4.00 | -- |
| Investment income, net of expenses | 1,165.00 | 1,025.00 | 894.00 | 781.00 | 714.00 | 670.00 | 646.00 | 619.00 | 609.00 | 595.00 |
| Interest | 875.00 | 733.00 | 600.00 | 510.00 | 477.00 | 455.00 | 446.00 | 445.00 | 445.00 | 440.00 |
| Dividends | 280.00 | 283.00 | 282.00 | 275.00 | 246.00 | 220.00 | 201.00 | 181.00 | 170.00 | 161.00 |
| Investment expenses | 17.00 | 16.00 | 13.00 | 15.00 | 14.00 | 13.00 | 13.00 | 12.00 | 10.00 | 9.00 |
| Fee revenues | 20.00 | 17.00 | 21.00 | 14.00 | 15.00 | 11.00 | 15.00 | 15.00 | 16.00 | 15.00 |
| Other income (loss) | 21.00 | 15.00 | 13.00 | 10.00 | 10.00 | 10.00 | 9.00 | 5.00 | 5.00 | 5.00 |
| Total Revenues | 12,631.00 | 11,337.00 | 10,013.00 | 6,557.00 | 9,630.00 | 7,536.00 | 7,924.00 | 5,407.00 | 5,732.00 | 5,449.00 |
| Insurance losses and policyholder benefits | 6,640.00 | 5,737.00 | 5,274.00 | 5,012.00 | 3,936.00 | 4,134.00 | 3,638.00 | 3,490.00 | 3,390.00 | 3,107.00 |
| Underwriting, acquisition and insurance expenses | 2,924.00 | 2,657.00 | 2,384.00 | 2,162.00 | 1,951.00 | 1,829.00 | 1,738.00 | 1,597.00 | 1,546.00 | 1,465.00 |
| Increase in deferred policy acquisition costs | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Other operating expenses | (34.00) | (32.00) | (25.00) | (23.00) | (20.00) | (20.00) | (23.00) | (16.00) | (13.00) | (12.00) |
| Other Expenses | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Commissions | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Interest expense | 53.00 | 53.00 | 54.00 | 53.00 | 53.00 | 54.00 | 53.00 | 53.00 | 53.00 | 53.00 |
| Taxes, licenses and fees | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Asset impairment-software written off | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Income before income taxes | 2,980.00 | 2,858.00 | 2,276.00 | (693.00) | 3,670.00 | 1,499.00 | 2,472.00 | 251.00 | 730.00 | 812.00 |
| Commercial lines insurance | 439.00 | 311.00 | 168.00 | 38.00 | 598.00 | 64.00 | 241.00 | 151.00 | 119.00 | 184.00 |
| Personal lines insurance | (111.00) | 71.00 | (4.00) | 18.00 | 97.00 | 47.00 | 8.00 | (20.00) | (32.00) | (12.00) |
| Life insurance | 65.00 | 57.00 | 41.00 | 28.00 | (16.00) | 11.00 | 1.00 | 8.00 | (1.00) | 1.00 |
| Investment operations | 2,480.00 | 2,291.00 | 1,900.00 | (795.00) | 3,018.00 | 1,433.00 | 2,197.00 | 121.00 | 664.00 | 629.00 |
| Pre-Tax Income: Other | 22.00 | 88.00 | 117.00 | -- | -- | -- | (28.00) | (72.00) | (81.00) | (52.00) |
| Property casualty insurance | -- | -- | -- | -- | -- | -- | -- | -- | -- | -- |
| Corporate and other | -- | -- | -- | (30.00) | (71.00) | (90.00) | -- | -- | -- | -- |
| Excess and surplus lines insurance | 85.00 | 40.00 | 54.00 | 48.00 | 44.00 | 34.00 | 53.00 | 63.00 | 61.00 | 62.00 |
| Provision for income taxes | 587.00 | 566.00 | 433.00 | (207.00) | 724.00 | 283.00 | 475.00 | (36.00) | (315.00) | 221.00 |
| Deferred: provision for income taxes | 304.00 | 117.00 | 223.00 | (355.00) | 477.00 | 136.00 | 343.00 | (47.00) | (444.00) | 38.00 |
| Current: provision for income taxes | 283.00 | 449.00 | 210.00 | 148.00 | 247.00 | 147.00 | 132.00 | 11.00 | 129.00 | 183.00 |
| Net income | 2,393.00 | 2,292.00 | 1,843.00 | (486.00) | 2,946.00 | 1,216.00 | 1,997.00 | 287.00 | 1,045.00 | 591.00 |
| Net income-basic | 15.32 | 14.65 | 11.74 | (3.06) | 18.29 | 7.55 | 12.24 | 1.76 | 6.36 | 3.59 |
| Net income-diluted | 15.17 | 14.53 | 11.66 | (3.06) | 18.10 | 7.49 | 12.10 | 1.75 | 6.29 | 3.55 |
| Weighted average shares outstanding | 156.10 | 156.40 | 157.00 | 158.80 | 161.00 | 161.20 | 163.20 | 163.20 | 164.20 | 164.50 |
| Weighted average shares outstanding-Diluted | 157.70 | 157.80 | 158.10 | 158.80 | 162.70 | 162.40 | 165.10 | 164.50 | 166.00 | 166.50 |