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Reserve for Loss and Loss Expense Reserve for Loss and Loss Expense (Claims Development) (Details)	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 ($)	Dec. 31, 2009 USD ($)
Claims Development [Line Items]
Net outstanding liabilities	$ 10,921,712,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	8,066,344,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,216,999,000
Reserve for loss and loss expense	3,893,868,000	$ 3,771,240,000
Short-duration Insurance Contracts, Accident Year 2009 [Member]
Claims Development [Line Items]
Net outstanding liabilities	846,017,000	848,413,000	$ 853,401,000	$ 857,960,000	$ 869,927,000	$ 870,057,000	$ 883,590,000	$ 916,691,000	$ 941,972,000	$ 920,143,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 34,771,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	85,707
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 791,281,000	784,713,000	775,885,000	760,589,000	736,100,000	695,249,000	634,902,000	540,982,000	442,417,000	277,275,000
Short-duration Insurance Contracts, Accident Year 2010 [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 42,224,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,400
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	1,013,115,000	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	$ 50,251,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	104,677
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 66,071,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	103,949
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 86,250,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	91,084
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	1,104,218,000	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	$ 117,760,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,774
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	1,138,313,000	1,144,830,000	1,130,513,000	1,114,081,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 175,271,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	93,673
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	1,227,142,000	1,203,634,000	1,188,608,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 319,825,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	93,724
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 764,331,000	617,958,000	387,272,000
Short-duration Insurance Contracts, Accident Year 2017 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,313,372,000	1,270,110,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 471,978,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	96,426
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 678,453,000	433,440,000
Short-duration Insurance Contracts, Accident Year 2018 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,413,800,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 677,444,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	96,408
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 511,271,000
Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	361,631,000
Standard Commercial Lines [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	2,361,691,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,277,379,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	1,175,230,000
Standard Commercial Lines [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,844,096,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,216,045,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	873,882,000
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	2,340,518,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,812,040,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	532,320,000
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	499,967,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	422,006,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	85,744,000
Standard Commercial Lines [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,222,005,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,163,094,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	58,980,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	203,176,000	201,568,000	205,741,000	206,387,000	211,243,000	212,947,000	223,146,000	233,530,000	241,625,000	237,913,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 15,951,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	13,873
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 183,263,000	180,621,000	176,316,000	166,767,000	151,920,000	130,554,000	103,213,000	64,970,000	37,143,000	14,346,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	205,125,000	208,142,000	208,611,000	212,536,000	216,992,000	210,756,000	210,109,000	213,036,000	215,946,000	197,504,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,242,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,218
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 171,205,000	167,894,000	164,336,000	160,529,000	154,726,000	145,417,000	133,116,000	117,019,000	87,299,000	37,885,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	161,057,000	161,300,000	161,923,000	161,251,000	162,911,000	166,682,000	169,858,000	182,724,000	191,079,000	199,541,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 574,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	24,749
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 160,456,000	160,013,000	159,723,000	158,303,000	155,560,000	149,949,000	137,564,000	113,697,000	94,406,000	63,126,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	44,028,000	43,933,000	44,273,000	44,299,000	44,938,000	43,553,000	43,828,000	46,645,000	51,762,000	48,535,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 323,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,474
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 43,596,000	43,547,000	43,448,000	43,358,000	42,895,000	40,052,000	36,073,000	32,689,000	29,612,000	18,915,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	80,410,000	80,416,000	80,545,000	80,558,000	80,455,000	80,774,000	82,014,000	82,025,000	82,124,000	82,619,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,009
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 80,393,000	80,405,000	80,509,000	80,529,000	80,352,000	80,251,000	80,894,000	80,433,000	78,695,000	59,933,000
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 18,634,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,696
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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 Year 2010 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 22,614,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	12,185
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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 Year 2010 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 762,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,406
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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 Year 2010 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 381,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,918
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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 Year 2010 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	7,668
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 20,973,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,614
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 26,226,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,850
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	173,507,000	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	$ 1,633,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,398
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	58,735,000	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	$ 1,140,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,959
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	131,009,000	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	$ 6,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,038
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 131,100,000	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	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	$ 25,251,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,960
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 30,444,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,613
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 2,259,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	24,025
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	43,418,000	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	$ 430,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,542
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	117,225,000	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	$ 21,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,515
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 35,971,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,326
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 30,648,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,372
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 3,756,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	25,556
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	39,709,000	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	$ 1,404,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,482
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	90,278,000	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	$ 28,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,713
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 90,696,000	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	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	$ 57,041,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,513
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 33,422,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,488
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 8,718,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	27,528
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	58,517,000	59,806,000	62,548,000	60,949,000	55,962,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,959,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,062
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 57,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,514
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	233,249,000	246,990,000	245,710,000	254,720,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 84,861,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,253
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	179,642,000	183,604,000	194,639,000	193,729,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 34,940,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,544
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	259,495,000	253,074,000	240,958,000	220,994,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 19,192,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	29,092
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	55,925,000	57,245,000	53,768,000	52,871,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,215,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,952
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	111,566,000	111,750,000	109,513,000	110,270,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 77,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,401
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	277,986,000	272,048,000	277,214,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 142,991,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,213
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	176,248,000	184,946,000	196,774,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 56,258,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,553
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	285,302,000	274,367,000	255,187,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 46,407,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	30,855
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	54,993,000	53,792,000	52,335,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 9,272,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,823
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	125,937,000	126,185,000	121,927,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 405,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,727
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	293,128,000	293,747,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 202,925,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,032
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	184,306,000	195,202,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 72,213,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,745
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	329,389,000	301,274,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 98,125,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	32,122
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	48,698,000	46,624,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 13,087,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,808
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	149,106,000	138,773,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ (76,000)
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,850
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	317,934,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 270,267,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,741
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	193,894,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 98,015,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,553
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	347,908,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 164,906,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	32,895
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	55,024,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 16,177,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,823
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	183,177,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 7,052,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,695
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 135,416,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	90,918,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	245,831,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	3,842,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	7,783,000
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	69,000
Standard Personal Lines [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,064,912,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	974,882,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	96,070,000
Standard Personal Lines [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	707,712,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	682,713,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	31,106,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	103,303,000	103,348,000	103,412,000	103,393,000	103,866,000	104,734,000	103,908,000	105,033,000	103,319,000	93,808,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 146,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	17,346
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 103,010,000	103,009,000	102,437,000	102,322,000	102,187,000	100,566,000	96,229,000	86,431,000	71,911,000	51,039,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	40,500,000	40,451,000	40,457,000	40,465,000	40,400,000	61,927,000	40,313,000	42,609,000	44,511,000	47,636,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 70,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,634
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 40,403,000	40,269,000	40,189,000	39,907,000	39,819,000	39,731,000	39,342,000	38,078,000	36,965,000	$ 28,299,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	$ 160,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,822
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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 Year 2010 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	62,402,000	62,392,000	62,339,000	62,402,000	62,462,000	97,761,000	63,285,000	67,525,000	68,373,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 83,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,132
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 62,283,000	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	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	$ 194,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,700
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 113,664,000	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	94,587,000	94,378,000	94,183,000	94,543,000	94,167,000	82,744,000	98,211,000	103,804,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 131,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	15,109
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	109,795,000	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	$ 205,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,332
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 109,447,000	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	86,483,000	86,330,000	86,271,000	86,667,000	86,560,000	82,745,000	87,260,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 237,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	16,939
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	107,680,000	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	$ 288,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,373
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	72,148,000	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	$ 331,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,747
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 774,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,504
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	83,539,000	83,844,000	83,637,000	82,461,000	80,111,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 411,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,770
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	99,570,000	100,214,000	99,698,000	96,387,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,572,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,860
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	74,723,000	76,559,000	76,400,000	76,637,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,172,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,744
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	100,202,000	98,032,000	92,727,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,252,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	19,803
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	62,391,000	60,931,000	60,105,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,837,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,869
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	105,139,000	101,880,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 13,162,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,679
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	67,978,000	59,167,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,969,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,299
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	111,594,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 23,506,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	21,748
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 69,721,000
Standard Personal Lines [Member] | Short-duration Insurance Contracts, Accident Year 2018 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	62,961,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,660,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,062
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 49,430,000
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	6,040,000
Standard Personal Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | Homeowners [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	6,107,000
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	593,898,000
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	263,529,000
Liability for Unpaid Claims and Claims Adjustment Expense, Net	330,467,000
E&S Lines [Member] | Commercial Property [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	13,604,000
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	739,000	737,000	96,000	710,000	728,000	938,000	1,053,000	885,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 0
Short-duration Insurance Contract, Cumulative Number of Reported Claims	274
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 739,000	737,000	709,000	626,000	605,000	431,000	198,000	0
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2010 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	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	813
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 276,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,321
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	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	$ 6,417,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,022
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	68,972,000	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	$ 14,175,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,266
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	71,206,000	71,719,000	69,929,000	63,505,000	55,316,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 14,097,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,040
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	90,488,000	82,404,000	76,432,000	75,498,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 24,516,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,746
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	104,655,000	96,416,000	94,451,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 52,151,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,732
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	95,783,000	91,438,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 66,321,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,353
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 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	98,324,000
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 82,486,000
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,734
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 5,509,000
E&S Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2009 [Member] | General Liability [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	$ 98,000

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