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Reserve for Loss and Loss Expense (Claims Development) (Details) | Dec. 31, 2019 USD ($) | Dec. 31, 2018 USD ($) | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($) | Dec. 31, 2015 USD ($) | Dec. 31, 2014 USD ($) | Dec. 31, 2013 USD ($) | Dec. 31, 2012 USD ($) | Dec. 31, 2011 USD ($) | Dec. 31, 2010 USD ($)
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Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | $ 11,547,343,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 8,514,750,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 3,392,713,000 |  |  |  |  |  |  |  |  |
Reserve for loss and loss expense | 4,067,163,000 | $ 3,893,868,000 |  |  |  |  |  |  |  |
Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 360,119,000 |  |  |  |  |  |  |  |  |
Short-Duration Insurance Contracts, Accident Years 2010 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 902,258,000 | 904,561,000 | $ 907,074,000 | $ 915,131,000 | $ 922,404,000 | $ 943,118,000 | $ 956,600,000 | $ 977,959,000 | $ 973,742,000 | $ 950,114,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 38,152,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 94,526 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 851,633,000 | 846,386,000 | 835,532,000 | 823,770,000 | 803,773,000 | 773,536,000 | 704,895,000 | 625,229,000 | 509,910,000 | 328,826,000
Short-duration Insurance Contracts, Accident Year 2011 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,013,175,000 | 1,013,115,000 | 1,019,351,000 | 1,023,726,000 | 1,033,518,000 | 1,056,107,000 | 1,062,233,000 | 1,061,667,000 | 1,042,576,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 44,453,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 104,861 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 950,836,000 | 940,626,000 | 924,111,000 | 901,801,000 | 852,202,000 | 782,655,000 | 692,730,000 | 585,867,000 | 391,944,000 |
Short-duration Insurance Contracts, Accident Year 2012 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 968,536,000 | 973,411,000 | 973,644,000 | 973,089,000 | 998,028,000 | 1,020,655,000 | 1,071,290,000 | 1,065,437,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 50,942,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 104,148 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 898,269,000 | 879,372,000 | 856,195,000 | 810,135,000 | 743,742,000 | 651,544,000 | 555,819,000 | 378,067,000 |  |
Short-duration Insurance Contracts, Accident Year 2013 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 984,858,000 | 987,763,000 | 1,002,316,000 | 1,021,007,000 | 1,047,230,000 | 1,062,045,000 | 1,044,142,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 72,970,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 91,326 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 891,841,000 | 872,331,000 | 833,823,000 | 748,758,000 | 644,475,000 | 518,872,000 | 335,956,000 |  |  |
Short-duration Insurance Contracts, Accident Year 2014 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,100,208,000 | 1,104,218,000 | 1,124,014,000 | 1,146,990,000 | 1,133,798,000 | 1,107,513,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 83,392,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 95,081 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 981,868,000 | 936,425,000 | 855,959,000 | 736,154,000 | 614,075,000 | 405,898,000 |  |  |  |
Short-duration Insurance Contracts, Accident Year 2015 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,119,441,000 | 1,138,313,000 | 1,144,830,000 | 1,130,513,000 | 1,114,081,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 111,657,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 94,128 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 929,222,000 | 845,868,000 | 725,385,000 | 581,203,000 | 376,641,000 |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2016 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,199,734,000 | 1,227,142,000 | 1,203,634,000 | 1,188,608,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 205,126,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 94,579 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 892,390,000 | 764,331,000 | 617,958,000 | 387,272,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2017 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,313,585,000 | 1,313,372,000 | 1,270,110,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 336,155,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 98,014 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 829,134,000 | 678,453,000 | 433,440,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Accident Year 2018 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,461,603,000 | 1,413,800,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 501,519,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 104,187 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 779,466,000 | 511,271,000 |  |  |  |  |  |  |  |
Short-Duration Insurance Contract, Accident Year 2019 [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,483,945,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 759,853,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 93,947 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 510,091,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 2,508,023,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,321,589,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 1,280,416,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,789,692,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,179,326,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 850,505,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 2,566,548,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,973,765,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 596,686,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 512,159,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 432,942,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 86,747,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,320,677,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 1,268,844,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 52,071,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 93,982,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 240,140,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 3,904,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 7,530,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 237,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 205,322,000 | 206,146,000 | 202,394,000 | 208,968,000 | 211,619,000 | 222,328,000 | 237,154,000 | 242,499,000 | 228,680,000 | 215,208,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 17,542,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 12,705 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 185,962,000 | 183,988,000 | 178,179,000 | 172,394,000 | 161,487,000 | 143,360,000 | 113,050,000 | 80,018,000 | 46,201,000 | 15,726,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 197,095,000 | 199,539,000 | 204,423,000 | 208,155,000 | 212,448,000 | 214,916,000 | 211,030,000 | 212,815,000 | 214,469,000 | 198,371,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 19,514,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 12,192 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 167,478,000 | 165,526,000 | 162,796,000 | 158,078,000 | 153,795,000 | 149,086,000 | 137,184,000 | 122,442,000 | 93,281,000 | 46,795,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 172,995,000 | 173,080,000 | 173,471,000 | 173,157,000 | 172,969,000 | 179,854,000 | 181,923,000 | 187,778,000 | 189,305,000 | 187,562,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 682,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 25,512 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 171,941,000 | 171,693,000 | 169,793,000 | 169,100,000 | 167,227,000 | 163,513,000 | 146,913,000 | 128,015,000 | 99,254,000 | 68,098,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 41,156,000 | 40,920,000 | 41,197,000 | 41,239,000 | 40,581,000 | 40,899,000 | 39,915,000 | 42,408,000 | 49,285,000 | 53,669,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 333,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,920 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 40,823,000 | 40,439,000 | 40,395,000 | 40,279,000 | 38,900,000 | 37,819,000 | 34,705,000 | 31,027,000 | 28,131,000 | 20,821,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 95,338,000 | 95,142,000 | 95,155,000 | 95,178,000 | 95,363,000 | 95,530,000 | 96,127,000 | 97,386,000 | 96,851,000 | 105,647,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 4,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 7,669 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 95,334,000 | 95,138,000 | 95,150,000 | 95,156,000 | 95,147,000 | 95,270,000 | 95,111,000 | 94,602,000 | 91,918,000 | 69,543,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 213,485,000 | 211,500,000 | 212,011,000 | 211,196,000 | 217,256,000 | 230,785,000 | 239,480,000 | 228,720,000 | 227,769,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 19,913,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 11,649 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 187,276,000 | 181,856,000 | 170,525,000 | 159,768,000 | 135,377,000 | 102,978,000 | 73,643,000 | 42,692,000 | 13,924,000 |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 192,863,000 | 194,821,000 | 200,674,000 | 205,708,000 | 210,591,000 | 215,114,000 | 214,743,000 | 218,973,000 | 205,238,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 22,717,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 11,860 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 161,696,000 | 158,535,000 | 154,320,000 | 149,269,000 | 139,232,000 | 134,646,000 | 118,847,000 | 90,836,000 | 42,941,000 |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 173,401,000 | 173,507,000 | 174,514,000 | 174,882,000 | 172,617,000 | 178,421,000 | 182,325,000 | 183,044,000 | 174,006,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 899,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 25,524 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 172,365,000 | 170,913,000 | 170,000,000 | 166,082,000 | 157,291,000 | 142,507,000 | 121,576,000 | 99,196,000 | 69,849,000 |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 58,948,000 | 58,735,000 | 58,456,000 | 58,966,000 | 59,256,000 | 58,242,000 | 51,047,000 | 57,083,000 | 54,469,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 362,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 4,960 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 57,380,000 | 57,365,000 | 57,045,000 | 55,856,000 | 52,114,000 | 46,444,000 | 41,011,000 | 37,362,000 | 27,884,000 |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 131,002,000 | 131,009,000 | 131,049,000 | 131,113,000 | 131,353,000 | 131,282,000 | 130,942,000 | 131,667,000 | 136,954,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 7,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 9,038 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 131,092,000 | 131,100,000 | 131,089,000 | 131,115,000 | 131,060,000 | 130,681,000 | 129,579,000 | 127,580,000 | 94,538,000 |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 182,085,000 | 180,659,000 | 175,268,000 | 175,305,000 | 194,144,000 | 215,083,000 | 245,561,000 | 238,979,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 21,005,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 9,994 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 156,186,000 | 144,451,000 | 130,866,000 | 109,448,000 | 89,008,000 | 56,580,000 | 35,241,000 | 13,030,000 |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 178,774,000 | 183,314,000 | 187,359,000 | 188,596,000 | 195,197,000 | 199,360,000 | 208,036,000 | 203,864,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 24,605,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 11,618 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 146,739,000 | 143,281,000 | 139,477,000 | 132,052,000 | 122,755,000 | 108,211,000 | 86,909,000 | 40,911,000 |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 185,357,000 | 184,633,000 | 186,128,000 | 184,367,000 | 184,289,000 | 183,527,000 | 191,947,000 | 179,551,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 1,920,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 24,160 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 181,353,000 | 179,501,000 | 176,656,000 | 168,114,000 | 148,669,000 | 127,235,000 | 105,371,000 | 73,316,000 |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 43,717,000 | 43,418,000 | 43,747,000 | 44,077,000 | 44,172,000 | 46,303,000 | 48,029,000 | 54,342,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 703,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 5,543 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 41,356,000 | 41,326,000 | 40,627,000 | 38,766,000 | 37,215,000 | 35,089,000 | 31,833,000 | 22,199,000 |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 117,220,000 | 117,225,000 | 117,170,000 | 117,102,000 | 116,658,000 | 115,375,000 | 114,224,000 | 118,464,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 10,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 8,517 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 116,674,000 | 116,671,000 | 116,625,000 | 116,291,000 | 114,699,000 | 111,503,000 | 108,834,000 | 81,528,000 |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 202,697,000 | 203,831,000 | 210,785,000 | 225,709,000 | 239,776,000 | 251,421,000 | 250,609,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 28,857,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,378 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 163,764,000 | 153,628,000 | 139,114,000 | 104,587,000 | 72,127,000 | 35,113,000 | 12,789,000 |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 159,767,000 | 162,787,000 | 166,662,000 | 173,160,000 | 187,658,000 | 194,318,000 | 199,794,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 26,260,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 11,375 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 126,822,000 | 124,130,000 | 118,669,000 | 109,739,000 | 96,376,000 | 74,568,000 | 36,829,000 |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 209,602,000 | 207,975,000 | 210,410,000 | 207,994,000 | 209,197,000 | 205,282,000 | 188,289,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 2,928,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 25,722 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 202,622,000 | 200,750,000 | 189,626,000 | 169,850,000 | 140,015,000 | 109,893,000 | 76,469,000 |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 39,699,000 | 39,709,000 | 41,369,000 | 40,624,000 | 41,005,000 | 42,618,000 | 49,617,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 803,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,482 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 39,085,000 | 38,464,000 | 37,993,000 | 34,760,000 | 30,845,000 | 26,592,000 | 17,412,000 |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 90,218,000 | 90,278,000 | 90,436,000 | 90,005,000 | 90,103,000 | 90,639,000 | 88,101,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 18,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 5,713 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 90,646,000 | 90,696,000 | 90,840,000 | 90,350,000 | 90,446,000 | 87,874,000 | 60,244,000 |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 237,125,000 | 234,082,000 | 239,333,000 | 257,132,000 | 249,946,000 | 244,312,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 42,388,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,586 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 179,192,000 | 154,957,000 | 121,969,000 | 79,972,000 | 46,825,000 | 14,901,000 |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 160,646,000 | 164,420,000 | 172,515,000 | 182,579,000 | 187,065,000 | 199,346,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 28,320,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,495 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 124,077,000 | 119,392,000 | 113,626,000 | 100,876,000 | 78,944,000 | 35,924,000 |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 217,334,000 | 218,172,000 | 219,925,000 | 216,824,000 | 212,725,000 | 200,534,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 4,831,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 27,714 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 209,655,000 | 202,821,000 | 180,701,000 | 148,884,000 | 117,169,000 | 80,810,000 |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 58,093,000 | 58,517,000 | 59,806,000 | 62,548,000 | 60,949,000 | 55,962,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 1,390,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 4,064 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 55,458,000 | 52,940,000 | 49,460,000 | 44,911,000 | 40,584,000 | 28,914,000 |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 136,212,000 | 138,155,000 | 138,751,000 | 136,820,000 | 136,249,000 | 141,192,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 33,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,515 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 136,008,000 | 137,418,000 | 137,883,000 | 136,634,000 | 132,909,000 | 101,131,000 |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 219,204,000 | 233,249,000 | 246,990,000 | 245,710,000 | 254,720,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 55,244,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,381 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 144,216,000 | 116,804,000 | 78,668,000 | 39,978,000 | 14,665,000 |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 176,242,000 | 179,642,000 | 183,604,000 | 194,639,000 | 193,729,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 27,927,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,549 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 120,097,000 | 112,601,000 | 98,195,000 | 77,320,000 | 33,857,000 |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 260,565,000 | 259,495,000 | 253,074,000 | 240,958,000 | 220,994,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 7,966,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 29,340 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 238,142,000 | 211,515,000 | 175,866,000 | 132,260,000 | 91,347,000 |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 54,454,000 | 55,925,000 | 57,245,000 | 53,768,000 | 52,871,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 3,235,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,959 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 49,073,000 | 46,571,000 | 42,710,000 | 36,014,000 | 24,189,000 |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 112,496,000 | 111,566,000 | 111,750,000 | 109,513,000 | 110,270,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 56,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,404 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 110,969,000 | 110,994,000 | 109,829,000 | 106,182,000 | 79,048,000 |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 263,245,000 | 277,986,000 | 272,048,000 | 277,214,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 98,385,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,526 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 133,757,000 | 89,431,000 | 46,549,000 | 15,684,000 |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 166,009,000 | 176,248,000 | 184,946,000 | 196,774,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 41,146,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,572 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 109,166,000 | 98,037,000 | 78,531,000 | 34,525,000 |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 285,304,000 | 285,302,000 | 274,367,000 | 255,187,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 21,279,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 31,167 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 233,939,000 | 200,701,000 | 155,720,000 | 106,022,000 |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 53,835,000 | 54,993,000 | 53,792,000 | 52,335,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 4,245,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,843 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 45,308,000 | 39,973,000 | 36,848,000 | 24,655,000 |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 124,487,000 | 125,937,000 | 126,185,000 | 121,927,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ (96,000) |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,739 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 123,828,000 | 122,930,000 | 118,789,000 | 83,966,000 |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 301,384,000 | 293,128,000 | 293,747,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 161,114,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,706 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 92,355,000 | 49,470,000 | 17,366,000 |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 175,853,000 | 184,306,000 | 195,202,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 53,654,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,793 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 100,645,000 | 82,216,000 | 40,375,000 |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 324,291,000 | 329,389,000 | 301,274,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 57,165,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 32,474 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 220,422,000 | 178,823,000 | 117,287,000 |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 51,524,000 | 48,698,000 | 46,624,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 10,252,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,864 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 36,950,000 | 31,337,000 | 21,865,000 |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 149,044,000 | 149,106,000 | 138,773,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ (884,000) |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,886 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 148,589,000 | 142,338,000 | 99,047,000 |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 336,326,000 | 317,934,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 223,228,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 10,656 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 60,784,000 | 19,531,000 |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 193,818,000 | 193,894,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 74,399,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 11,078 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 84,780,000 | 41,122,000 |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 352,487,000 | 347,908,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 109,922,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 35,034 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 193,788,000 | 134,867,000 |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 57,202,000 | 55,024,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 12,432,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 4,159 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 39,791,000 | 29,995,000 |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 190,834,000 | 183,177,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ (329,000) |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 8,240 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 184,813,000 | 135,416,000 |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 347,150,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 296,257,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 8,626 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 18,097,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Workers Compensation [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 188,625,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 100,336,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 9,805 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 37,826,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Commercial Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 385,212,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 183,477,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 33,438 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 149,538,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Business Owners' Policies [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 53,531,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 15,068,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 3,210 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 27,718,000 |  |  |  |  |  |  |  |  |
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Commercial Property [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 173,826,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 15,732,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,722 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 130,891,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 1,076,685,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 983,814,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 100,331,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 739,559,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 713,124,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 31,752,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 7,462,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 5,316,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 106,785,000 | 106,887,000 | 107,054,000 | 107,224,000 | 107,405,000 | 107,490,000 | 109,515,000 | 112,346,000 | 110,075,000 | 103,340,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 64,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20,823 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 106,716,000 | 106,722,000 | 106,733,000 | 106,453,000 | 105,849,000 | 104,061,000 | 101,540,000 | 95,300,000 | 82,490,000 | 58,786,000
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 62,380,000 | 62,402,000 | 62,392,000 | 62,339,000 | 62,402,000 | 62,462,000 | 61,927,000 | 63,285,000 | 67,525,000 | 68,373,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 48,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 9,132 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 62,329,000 | 62,283,000 | 62,272,000 | 62,241,000 | 62,227,000 | 62,155,000 | 61,106,000 | 60,295,000 | 58,638,000 | $ 43,699,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 114,056,000 | 113,921,000 | 113,988,000 | 113,830,000 | 114,241,000 | 112,993,000 | 113,686,000 | 116,164,000 | 113,232,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 121,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 22,700 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 113,856,000 | 113,664,000 | 113,551,000 | 112,732,000 | 111,085,000 | 105,068,000 | 93,878,000 | 82,102,000 | 61,323,000 |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 94,572,000 | 94,587,000 | 94,378,000 | 94,183,000 | 94,543,000 | 94,167,000 | 97,761,000 | 98,211,000 | 103,804,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 82,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 15,111 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 94,458,000 | 94,412,000 | 94,007,000 | 93,720,000 | 93,312,000 | 92,185,000 | 91,718,000 | 89,963,000 | 71,668,000 |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 109,701,000 | 109,795,000 | 110,300,000 | 110,294,000 | 109,324,000 | 109,832,000 | 114,921,000 | 113,771,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 155,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 22,332 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 109,482,000 | 109,447,000 | 109,355,000 | 107,890,000 | 102,977,000 | 94,842,000 | 82,729,000 | 63,704,000 |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 86,567,000 | 86,483,000 | 86,330,000 | 86,271,000 | 86,667,000 | 86,560,000 | 82,744,000 | 87,260,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 94,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 16,941 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 85,897,000 | 85,642,000 | 85,562,000 | 85,196,000 | 84,250,000 | 82,720,000 | 79,584,000 | 69,056,000 |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 107,916,000 | 107,680,000 | 107,759,000 | 106,703,000 | 106,225,000 | 109,620,000 | 108,417,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 348,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 22,375 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 106,876,000 | 106,679,000 | 105,131,000 | 100,528,000 | 92,637,000 | 80,861,000 | 61,384,000 |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 72,318,000 | 72,148,000 | 71,714,000 | 72,145,000 | 71,494,000 | 72,528,000 | 73,670,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 420,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 7,749 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 72,433,000 | 72,197,000 | 71,776,000 | 69,775,000 | 67,838,000 | 65,528,000 | 50,664,000 |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 107,104,000 | 106,821,000 | 107,452,000 | 106,757,000 | 109,325,000 | 102,250,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 307,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 22,506 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 105,709,000 | 104,055,000 | 99,173,000 | 92,589,000 | 83,739,000 | 62,519,000 |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 83,824,000 | 83,539,000 | 83,844,000 | 83,637,000 | 82,461,000 | 80,111,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 682,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 8,773 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 82,836,000 | 82,583,000 | 81,664,000 | 79,751,000 | 76,007,000 | 61,561,000 |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 98,718,000 | 99,570,000 | 100,214,000 | 99,698,000 | 96,387,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 742,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20,863 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 95,997,000 | 92,102,000 | 87,163,000 | 76,470,000 | 58,725,000 |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 74,978,000 | 74,723,000 | 76,559,000 | 76,400,000 | 76,637,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 660,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 7,746 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 74,079,000 | 72,927,000 | 72,202,000 | 70,078,000 | 52,589,000 |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 101,140,000 | 100,202,000 | 98,032,000 | 92,727,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 2,565,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 19,819 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 94,372,000 | 86,752,000 | 76,823,000 | 57,961,000 |  |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 61,723,000 | 62,391,000 | 60,931,000 | 60,105,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 1,221,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,885 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 60,082,000 | 59,546,000 | 57,333,000 | 42,252,000 |  |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 103,653,000 | 105,139,000 | 101,880,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 6,342,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 20,725 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 91,479,000 | 82,730,000 | 62,854,000 |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 70,365,000 | 67,978,000 | 59,167,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 2,500,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 7,370 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 67,193,000 | 63,290,000 | 45,466,000 |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 113,569,000 | 111,594,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 14,259,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 22,621 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 89,628,000 | 69,721,000 |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 68,526,000 | 62,961,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 2,366,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 7,554 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 64,137,000 | 49,430,000 |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Personal Automobile [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 114,043,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 25,832,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 21,988 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 69,699,000 |  |  |  |  |  |  |  |  |
Standard Personal Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Homeowners [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 64,306,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 6,299,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 6,468 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 49,680,000 |  |  |  |  |  |  |  |  |
E&S Lines [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Reserve for loss and loss expense |  |  |  |  |  |  |  |  | 15,000,000 |
E&S Lines [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 716,746,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | 350,912,000 |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 365,943,000 |  |  |  |  |  |  |  |  |
E&S Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2010 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Liability for Unpaid Claims and Claims Adjustment Expense, Net | 109,000 |  |  |  |  |  |  |  |  |
E&S Lines [Member] | Short-Duration Insurance Contracts, Accident Years 2010 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 5,534,000 | 5,168,000 | 4,932,000 | 3,055,000 | 3,831,000 | 4,299,000 | 3,369,000 | 4,106,000 | 3,294,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 0 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 815 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 5,362,000 | 4,908,000 | 4,610,000 | 4,513,000 | 4,078,000 | 3,574,000 | 2,570,000 | 1,218,000 | 0 |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2011 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 11,554,000 | 12,119,000 | 10,228,000 | 9,652,000 | 10,273,000 | 12,207,000 | 9,853,000 | 7,102,000 | 8,127,000 |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 177,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,332 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 9,604,000 | 9,819,000 | 10,256,000 | 9,912,000 | 9,954,000 | 6,445,000 | 3,200,000 | 806,000 | $ 0 |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2012 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 44,622,000 | 46,444,000 | 45,988,000 | 46,165,000 | 46,149,000 | 43,175,000 | 42,621,000 | 42,367,000 |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 2,474,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,045 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 39,832,000 | 38,298,000 | 36,278,000 | 32,343,000 | 25,064,000 | 16,430,000 | 7,914,000 | $ 3,722,000 |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 68,451,000 | 68,972,000 | 67,647,000 | 69,112,000 | 67,099,000 | 60,309,000 | 55,468,000 |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 13,816,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,280 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 54,974,000 | 51,142,000 | 46,108,000 | 35,200,000 | 21,980,000 | 9,470,000 | $ 2,715,000 |  |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 71,153,000 | 71,206,000 | 71,719,000 | 69,929,000 | 63,505,000 | 55,316,000 |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 5,559,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,071 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 60,092,000 | 53,780,000 | 43,877,000 | 25,571,000 | 12,234,000 | $ 2,353,000 |  |  |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 90,355,000 | 90,488,000 | 82,404,000 | 76,432,000 | 75,498,000 |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 15,752,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,799 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 64,529,000 | 50,712,000 | 29,389,000 | 13,057,000 | $ 3,036,000 |  |  |  |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 105,120,000 | 104,655,000 | 96,416,000 | 94,451,000 |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 35,987,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,859 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 56,581,000 | 33,950,000 | 16,195,000 | $ 3,720,000 |  |  |  |  |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 99,866,000 | 95,783,000 | 91,438,000 |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 47,074,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,614 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 34,179,000 | 14,672,000 | $ 5,057,000 |  |  |  |  |  |  |
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 103,004,000 | 98,324,000 |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 62,754,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 2,392 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 21,337,000 | $ 5,509,000 |  |  |  |  |  |  |  |
E&S Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | General Liability [Member] |  |  |  |  |  |  |  |  |  |
Claims Development [Line Items] |  |  |  |  |  |  |  |  |  |
Net outstanding liabilities | 117,087,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net | $ 103,146,000 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contract, Cumulative Number of Reported Claims | 1,679 |  |  |  |  |  |  |  |  |
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net | $ 4,422,000 |  |  |  |  |  |  |  |  |

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