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Reserve for Loss and Loss Expense (Claims Development) (Details) $ in Thousands	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Net outstanding liabilities	$ 13,946,270
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	10,066,069
Liability for Unpaid Claims and Claims Adjustment Expense, Net	4,259,274
Reserve for loss and loss expense	5,144,821	$ 4,580,903
Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	379,073
Short-duration Insurance Contracts, Accident Year 2013 [Member]
Claims Development [Line Items]
Net outstanding liabilities	951,813	957,958	$ 973,739	$ 984,858	$ 987,763	$ 1,002,316	$ 1,021,007	$ 1,047,230	$ 1,062,045	$ 1,044,142
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 33,631
Short-duration Insurance Contract, Cumulative Number of Reported Claims	91,959
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 916,769	911,657	904,825	891,841	872,331	833,823	748,758	644,475	518,872	335,956
Short-duration Insurance Contracts, Accident Year 2014[Member]
Claims Development [Line Items]
Net outstanding liabilities	1,090,345	1,094,367	1,089,529	1,100,208	1,104,218	1,124,014	1,146,990	1,133,798	1,107,513
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 42,087
Short-duration Insurance Contract, Cumulative Number of Reported Claims	95,835
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,032,400	1,020,961	1,002,157	981,868	936,425	855,959	736,154	614,075	405,898
Short-duration Insurance Contracts, Accident Year 2015 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,103,543	1,103,592	1,108,860	1,119,441	1,138,313	1,144,830	1,130,513	1,114,081
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 45,698
Short-duration Insurance Contract, Cumulative Number of Reported Claims	95,173
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,018,023	1,000,509	967,857	929,222	845,868	725,385	581,203	376,641
Short-duration Insurance Contracts, Accident Year 2016 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,167,539	1,171,273	1,180,829	1,199,734	1,227,142	1,203,634	1,188,608
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 67,934
Short-duration Insurance Contract, Cumulative Number of Reported Claims	95,944
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,061,952	1,025,264	983,852	892,390	764,331	617,958	387,272
Short-duration Insurance Contracts, Accident Year 2017 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,273,039	1,268,941	1,288,526	1,313,585	1,313,372	1,270,110
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 84,415
Short-duration Insurance Contract, Cumulative Number of Reported Claims	99,877
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,116,336	1,050,258	954,792	829,134	678,453	433,440
Short-duration Insurance Contract, Accident Year 2018 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,425,540	1,441,303	1,457,415	1,461,603	1,413,800
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 153,214
Short-duration Insurance Contract, Cumulative Number of Reported Claims	107,095
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,187,744	1,083,556	942,893	779,466	511,271
Short-Duration Insurance Contract, Accident Year 2019 [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,529,859	1,526,566	1,523,041	1,483,945
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 272,639
Short-duration Insurance Contract, Cumulative Number of Reported Claims	104,096
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 1,109,628	949,996	781,462	510,091
Short-Duration Insurance Contract, Accident Year 2020
Claims Development [Line Items]
Net outstanding liabilities	1,550,195	1,587,607	1,591,972
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 395,519
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,752
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 988,463	831,976	572,302
Short-Duration Insurance Contract, Accident Year 2021
Claims Development [Line Items]
Net outstanding liabilities	1,781,054	1,784,661
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 636,984
Short-duration Insurance Contract, Cumulative Number of Reported Claims	97,914
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 934,965	609,889
Short-Duration Insurance Contract, Accident Year 2022
Claims Development [Line Items]
Net outstanding liabilities	2,073,343
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,089,571
Short-duration Insurance Contract, Cumulative Number of Reported Claims	94,382
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 699,789
Standard Commercial Lines [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	3,096,166
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,520,784
Liability for Unpaid Claims and Claims Adjustment Expense, Net	1,688,645
Standard Commercial Lines [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,665,144
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,086,983
Liability for Unpaid Claims and Claims Adjustment Expense, Net	809,019
Standard Commercial Lines [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	3,521,080
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	2,677,763
Liability for Unpaid Claims and Claims Adjustment Expense, Net	847,967
Standard Commercial Lines [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	589,734
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	488,920
Liability for Unpaid Claims and Claims Adjustment Expense, Net	110,471
Standard Commercial Lines [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,758,159
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	1,628,461
Liability for Unpaid Claims and Claims Adjustment Expense, Net	130,277
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | General Liability [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	113,263
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	230,858
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	4,650
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	9,657
Standard Commercial Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	579
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	189,594	192,782	195,697	202,697	203,831	210,785	225,709	239,776	251,421	250,609
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 12,561
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,462
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 174,987	172,983	169,847	163,764	153,628	139,114	104,587	72,127	35,113	12,789
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	149,975	153,436	157,645	159,767	162,787	166,662	173,160	187,658	194,318	199,794
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 16,818
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,385
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 131,390	130,467	129,224	126,822	124,130	118,669	109,739	96,376	74,568	36,829
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	207,564	207,554	208,040	209,602	207,975	210,410	207,994	209,197	205,282	188,289
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 535
Short-duration Insurance Contract, Cumulative Number of Reported Claims	26,221
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 206,641	206,162	205,064	202,622	200,750	189,626	169,850	140,015	109,893	76,469
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	38,984	38,930	39,358	39,699	39,709	41,369	40,624	41,005	42,618	49,617
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 169
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,484
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 39,445	39,440	39,212	39,085	38,464	37,993	34,760	30,845	26,592	17,412
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	90,799	90,461	90,486	90,218	90,278	90,436	90,005	90,103	90,639	88,101
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,716
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 91,206	90,891	90,917	90,646	90,696	90,840	90,350	90,446	87,874	60,244
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	228,933	230,247	229,679	237,125	234,082	239,333	257,132	249,946	244,312
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,901
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,704
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 204,212	198,772	187,352	179,192	154,957	121,969	79,972	46,825	14,901
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	158,479	161,021	159,604	160,646	164,420	172,515	182,579	187,065	199,346
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 17,598
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,498
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 132,809	130,726	127,858	124,077	119,392	113,626	100,876	78,944	35,924
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	214,816	214,992	216,461	217,334	218,172	219,925	216,824	212,725	200,534
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 516
Short-duration Insurance Contract, Cumulative Number of Reported Claims	28,263
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 213,847	213,689	212,481	209,655	202,821	180,701	148,884	117,169	80,810
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	57,355	57,483	57,302	58,093	58,517	59,806	62,548	60,949	55,962
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 96
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,067
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 56,861	55,729	55,708	55,458	52,940	49,460	44,911	40,584	28,914
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	136,112	136,151	136,237	136,212	138,155	138,751	136,820	136,249	141,192
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 5
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,517
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 136,107	136,141	135,928	136,008	137,418	137,883	136,634	132,909	101,131
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	210,137	211,768	214,176	219,204	233,249	246,990	245,710	254,720
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 19,932
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,565
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 179,117	173,697	157,071	144,216	116,804	78,668	39,978	14,665
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	169,008	170,577	172,572	176,242	179,642	183,604	194,639	193,729
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 18,790
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,554
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 132,235	129,019	124,046	120,097	112,601	98,195	77,320	33,857
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	262,766	262,054	261,386	260,565	259,495	253,074	240,958	220,994
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,627
Short-duration Insurance Contract, Cumulative Number of Reported Claims	30,085
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 257,668	255,600	249,905	238,142	211,515	175,866	132,260	91,347
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	52,514	52,200	52,325	54,454	55,925	57,245	53,768	52,871
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 608
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,968
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 51,120	50,005	49,839	49,073	46,571	42,710	36,014	24,189
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	112,915	112,937	112,582	112,496	111,566	111,750	109,513	110,270
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 9
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,407
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 112,391	112,410	112,117	110,969	110,994	109,829	106,182	79,048
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	243,669	246,643	252,733	263,245	277,986	272,048	277,214
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 30,556
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,825
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 199,032	181,770	164,136	133,757	89,431	46,549	15,684
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	151,961	155,210	156,540	166,009	176,248	184,946	196,774
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 21,205
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,586
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 122,186	119,800	115,159	109,166	98,037	78,531	34,525
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	294,297	291,674	290,359	285,304	285,302	274,367	255,187
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,635
Short-duration Insurance Contract, Cumulative Number of Reported Claims	32,041
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 284,870	277,242	264,858	233,939	200,701	155,720	106,022
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	53,201	53,147	53,367	53,835	54,993	53,792	52,335
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 828
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,854
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 52,070	50,536	48,786	45,308	39,973	36,848	24,655
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	123,126	123,005	123,567	124,487	125,937	126,185	121,927
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 14
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,743
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 123,265	122,909	123,601	123,828	122,930	118,789	83,966
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	283,379	278,607	289,883	301,384	293,128	293,747
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 46,761
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,324
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 201,948	167,002	131,980	92,355	49,470	17,366
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	151,221	154,159	162,672	175,853	184,306	195,202
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 19,961
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,813
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 120,468	116,426	110,645	100,645	82,216	40,375
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	325,654	326,461	322,197	324,291	329,389	301,274
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,664
Short-duration Insurance Contract, Cumulative Number of Reported Claims	33,345
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 309,810	296,600	262,349	220,422	178,823	117,287
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	42,374	43,606	48,067	51,524	48,698	46,624
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 879
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,895
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 40,845	39,940	40,359	36,950	31,337	21,865
Standard Commercial Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	154,942	154,119	153,664	149,044	149,106	138,773
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 20
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,906
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 154,689	153,750	152,018	148,589	142,338	99,047
Standard Commercial Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	324,567	332,013	345,224	336,326	317,934
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 92,627
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,802
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 197,286	155,538	108,421	60,784	19,531
Standard Commercial Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	167,974	173,428	181,151	193,818	193,894
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 25,963
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,133
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 126,206	119,904	105,903	84,780	41,122
Standard Commercial Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	348,202	350,310	345,547	352,487	347,908
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 11,375
Short-duration Insurance Contract, Cumulative Number of Reported Claims	36,002
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 319,819	291,725	243,713	193,788	134,867
Standard Commercial Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	56,625	60,393	62,427	57,202	55,024
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 3,125
Short-duration Insurance Contract, Cumulative Number of Reported Claims	4,262
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 51,239	48,144	44,316	39,791	29,995
Standard Commercial Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	196,413	194,016	192,558	190,834	183,177
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 47
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,293
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 196,376	193,487	192,698	184,813	135,416
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	366,184	358,301	356,363	347,150
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 154,311
Short-duration Insurance Contract, Cumulative Number of Reported Claims	11,575
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 160,680	100,206	58,284	18,097
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	164,940	174,912	188,596	188,625
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 32,088
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,324
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 112,649	100,812	77,878	37,826
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	407,051	404,854	398,346	385,212
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 32,019
Short-duration Insurance Contract, Cumulative Number of Reported Claims	36,375
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 331,152	283,410	221,590	149,538
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	65,762	64,667	59,466	53,531
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 8,181
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,639
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 52,887	46,113	41,587	27,718
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	180,605	179,574	177,075	173,826
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 230
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,315
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 179,538	177,825	172,768	130,891
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	352,834	360,302	361,554
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 201,089
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,645
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 100,356	58,699	21,858
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	159,229	168,594	168,643
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 44,323
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,534
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 87,211	68,277	29,559
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	375,636	381,163	381,654
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 70,872
Short-duration Insurance Contract, Cumulative Number of Reported Claims	30,343
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 254,365	198,034	139,016
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	73,077	73,680	71,836
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 7,630
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,421
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 60,596	57,210	43,376
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	226,107	225,278	232,060
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,023
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,147
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 220,953	215,107	164,613
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	414,279	422,748
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 287,278
Short-duration Insurance Contract, Cumulative Number of Reported Claims	10,136
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 71,664	28,069
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	185,151	185,198
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 74,474
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,547
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 76,015	32,918
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	512,673	483,831
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 155,984
Short-duration Insurance Contract, Cumulative Number of Reported Claims	36,843
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 283,411	187,200
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	63,648	66,312
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 10,539
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,454
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 47,436	34,412
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	239,822	246,319
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,672
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,942
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 227,259	161,757
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | General Liability [Member]
Claims Development [Line Items]
Net outstanding liabilities	482,590
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 409,505
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,988
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 31,502
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | Workers Compensation [Member]
Claims Development [Line Items]
Net outstanding liabilities	207,206
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 116,968
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,517
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 45,814
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | Commercial Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	572,421
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 278,004
Short-duration Insurance Contract, Cumulative Number of Reported Claims	36,909
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 216,180
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | Business Owners' Policies [Member]
Claims Development [Line Items]
Net outstanding liabilities	86,194
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 33,995
Short-duration Insurance Contract, Cumulative Number of Reported Claims	3,074
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 36,421
Standard Commercial Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | Commercial Property [Member]
Claims Development [Line Items]
Net outstanding liabilities	297,318
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 56,716
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,224
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 186,677
Standard Personal Lines | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,065,746
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	972,809
Liability for Unpaid Claims and Claims Adjustment Expense, Net	99,982
Standard Personal Lines | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	792,170
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	752,675
Liability for Unpaid Claims and Claims Adjustment Expense, Net	45,597
Standard Personal Lines | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	7,045
Standard Personal Lines | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Homeowners [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	6,102
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	107,758	107,754	107,803	107,916	107,680	107,759	106,703	106,225	109,620	108,417
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 57
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,376
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 107,417	107,423	107,419	106,876	106,679	105,131	100,528	92,637	80,861	61,384
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	71,960	71,955	71,948	72,318	72,148	71,714	72,145	71,494	72,528	73,670
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 67
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,753
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 72,415	72,447	72,446	72,433	72,197	71,776	69,775	67,838	65,528	50,664
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2014[Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	107,543	107,566	107,106	107,104	106,821	107,452	106,757	109,325	102,250
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 47
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,509
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 107,325	107,108	106,478	105,709	104,055	99,173	92,589	83,739	62,519
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2014[Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	83,819	83,830	83,525	83,824	83,539	83,844	83,637	82,461	80,111
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 60
Short-duration Insurance Contract, Cumulative Number of Reported Claims	8,776
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 83,782	83,321	82,831	82,836	82,583	81,664	79,751	76,007	61,561
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	98,669	98,596	98,588	98,718	99,570	100,214	99,698	96,387
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 117
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,865
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 97,920	97,761	97,275	95,997	92,102	87,163	76,470	58,725
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	74,237	74,682	74,673	74,978	74,723	76,559	76,400	76,637
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 20
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,753
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 74,108	74,096	74,052	74,079	72,927	72,202	70,078	52,589
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	100,395	99,858	99,544	101,140	100,202	98,032	92,727
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 409
Short-duration Insurance Contract, Cumulative Number of Reported Claims	19,827
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 99,656	98,977	98,080	94,372	86,752	76,823	57,961
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	60,841	60,855	61,735	61,723	62,391	60,931	60,105
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 438
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,896
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 60,474	60,449	61,187	60,082	59,546	57,333	42,252
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	105,079	103,557	103,260	103,653	105,139	101,880
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 710
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,748
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 103,556	100,521	97,628	91,479	82,730	62,854
Standard Personal Lines | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	68,902	68,938	70,064	70,365	67,978	59,167
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 504
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,389
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 68,282	68,078	67,767	67,193	63,290	45,466
Standard Personal Lines | Short-duration Insurance Contract, Accident Year 2018 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	113,647	112,418	112,030	113,569	111,594
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 2,098
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,684
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 109,644	107,026	99,982	89,628	69,721
Standard Personal Lines | Short-duration Insurance Contract, Accident Year 2018 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	68,416	68,931	69,832	68,526	62,961
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 608
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,608
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 67,739	66,634	65,348	64,137	49,430
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	118,669	115,993	115,688	114,043
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,163
Short-duration Insurance Contract, Cumulative Number of Reported Claims	22,860
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 109,844	102,930	92,162	69,699
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	73,070	73,816	72,772	64,306
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 1,412
Short-duration Insurance Contract, Cumulative Number of Reported Claims	7,010
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 70,880	69,911	67,631	49,680
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2020 | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	90,179	94,532	95,625
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 6,584
Short-duration Insurance Contract, Cumulative Number of Reported Claims	17,533
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 76,710	68,691	53,407
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2020 | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	113,804	112,523	109,033
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 3,611
Short-duration Insurance Contract, Cumulative Number of Reported Claims	9,824
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 109,145	105,690	83,838
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2021 | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	102,777	108,244
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 10,411
Short-duration Insurance Contract, Cumulative Number of Reported Claims	19,672
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 84,743	65,325
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2021 | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	83,295	82,425
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 3,657
Short-duration Insurance Contract, Cumulative Number of Reported Claims	6,884
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 77,018	59,054
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2022 | Personal Automobile [Member]
Claims Development [Line Items]
Net outstanding liabilities	121,030
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 26,632
Short-duration Insurance Contract, Cumulative Number of Reported Claims	20,345
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 75,994
Standard Personal Lines | Short-Duration Insurance Contract, Accident Year 2022 | Homeowners [Member]
Claims Development [Line Items]
Net outstanding liabilities	93,826
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 17,362
Short-duration Insurance Contract, Cumulative Number of Reported Claims	5,819
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 68,832
E&S Lines [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	1,020,366
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	546,850
Liability for Unpaid Claims and Claims Adjustment Expense, Net	479,507
E&S Lines [Member] | Short-Duration Insurance Contracts, Accident Years Prior to 2013 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Liability for Unpaid Claims and Claims Adjustment Expense, Net	5,991
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2013 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	60,511	60,349	68,029	68,451	68,972	67,647	69,112	67,099	60,309	55,468
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 3,504
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,311
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 58,584	57,152	55,988	54,974	51,142	46,108	35,200	21,980	9,470	$ 2,715
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2014[Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	74,538	74,270	70,846	71,153	71,206	71,719	69,929	63,505	55,316
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,918
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,141
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 68,648	66,661	64,698	60,092	53,780	43,877	25,571	12,234	$ 2,353
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2015 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	90,263	87,662	90,126	90,355	90,488	82,404	76,432	75,498
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 4,646
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,887
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 81,396	75,844	71,421	64,529	50,712	29,389	13,057	$ 3,036
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2016 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	101,873	102,476	104,730	105,120	104,655	96,416	94,451
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 12,138
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,998
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 81,932	75,004	69,448	56,581	33,950	16,195	$ 3,720
E&S Lines [Member] | Short-duration Insurance Contracts, Accident Year 2017 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	102,045	99,960	99,395	99,866	95,783	91,438
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 11,390
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,848
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 77,090	68,266	53,238	34,179	14,672	$ 5,057
E&S Lines [Member] | Short-duration Insurance Contract, Accident Year 2018 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	105,756	104,983	103,184	103,004	98,324
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 17,093
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,816
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 73,605	57,962	39,174	21,337	$ 5,509
E&S Lines [Member] | Short-Duration Insurance Contract, Accident Year 2019 [Member] | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	117,113	117,736	118,298	117,087
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 39,429
Short-duration Insurance Contract, Cumulative Number of Reported Claims	2,683
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 57,701	35,844	17,812	$ 4,422
E&S Lines [Member] | Short-Duration Insurance Contract, Accident Year 2020 | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	95,832	103,137	103,872
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 49,633
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,788
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 27,861	13,064	$ 3,695
E&S Lines [Member] | Short-Duration Insurance Contract, Accident Year 2021 | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	125,436	128,099
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 89,909
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,751
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 15,835	$ 4,326
E&S Lines [Member] | Short-Duration Insurance Contract, Accident Year 2022 | Casualty Insurance Product Line [Member]
Claims Development [Line Items]
Net outstanding liabilities	146,999
Short-duration Insurance Contracts, Incurred but Not Reported (IBNR) Claims Liability, Net	$ 132,276
Short-duration Insurance Contract, Cumulative Number of Reported Claims	1,285
Short-duration Insurance Contracts, Cumulative Paid Claims and Allocated Claim Adjustment Expense, Net	$ 4,198

X

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_ClaimsDevelopmentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The amount needed to reflect the estimated ultimate cost of settling claims relating to casualty insurance insured events that have occurred on or before a particular date (ordinarily, the balance sheet date) and the amount needed to provide for the estimated ultimate cost required to investigate and settle claims relating to insured events that have occurred on or before a particular date (ordinarily, the balance sheet date), whether or not reported to the insurer at that date.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 40
-Section 50
-Paragraph 3
-Subparagraph (cc)
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