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RESERVE FOR LOSSES AND LOSS EXPENSES - Incurred claims and allocated claim adjustment expenses, net of reinsurance (Details) $ in Thousands	Dec. 31, 2020 USD ($) claim	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)
Insurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 4,584,024
Insurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	277,515	$ 277,792	$ 278,688	$ 280,395	$ 279,964	$ 281,155	$ 284,201	$ 304,702	$ 325,274	$ 347,569
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (231)
Cumulative number of reported claims | claim	6,367
Insurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 343,619	343,934	353,971	354,801	360,525	364,667	385,068	403,254	393,170
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (21)
Cumulative number of reported claims | claim	29,942
Insurance | Property and other | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 275,712	276,229	279,922	269,490	269,831	273,775	300,682	310,601
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,135
Cumulative number of reported claims | claim	53,204
Insurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 323,736	328,404	330,011	331,142	347,227	357,885	362,684
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 4,334
Cumulative number of reported claims | claim	62,371
Insurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 257,419	255,319	258,190	262,733	273,606	280,489
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,763
Cumulative number of reported claims | claim	48,469
Insurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 356,016	362,103	375,260	384,230	355,771
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,427
Cumulative number of reported claims | claim	93,792
Insurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 813,005	824,039	838,640	911,274
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (5,501)
Cumulative number of reported claims | claim	698,289
Insurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 754,741	775,861	742,601
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 10,217
Cumulative number of reported claims | claim	731,142
Insurance | Property and other | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 448,467	454,386
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 11,186
Cumulative number of reported claims | claim	659,908
Insurance | Property and other | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 733,794
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 308,515
Cumulative number of reported claims | claim	524,539
Insurance | Marine
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 1,132,710
Insurance | Marine | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	67,054	68,861	69,555	68,860	66,560	66,320	66,351	73,257	79,215	90,960
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (1,250)
Cumulative number of reported claims | claim	3,830
Insurance | Marine | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 66,026	63,067	73,581	75,326	72,708	71,663	69,484	83,431	89,889
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 7,249
Cumulative number of reported claims | claim	4,135
Insurance | Marine | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 81,774	82,622	83,594	83,984	98,759	97,660	102,110	80,641
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 846
Cumulative number of reported claims | claim	2,354
Insurance | Marine | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 42,221	48,470	46,705	44,979	49,238	44,936	59,786
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (2,231)
Cumulative number of reported claims | claim	2,166
Insurance | Marine | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 123,836	118,861	131,483	138,704	142,383	160,793
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 7,507
Cumulative number of reported claims | claim	2,231
Insurance | Marine | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 70,491	71,694	76,805	78,953	86,464
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,300
Cumulative number of reported claims | claim	2,857
Insurance | Marine | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 158,812	160,919	172,077	207,378
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 13,932
Cumulative number of reported claims | claim	4,005
Insurance | Marine | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 183,415	194,257	186,550
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 34,579
Cumulative number of reported claims | claim	4,370
Insurance | Marine | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 168,318	170,489
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 47,064
Cumulative number of reported claims | claim	4,475
Insurance | Marine | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 170,763
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 107,624
Cumulative number of reported claims | claim	3,558
Insurance | Aviation
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 321,164
Insurance | Aviation | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	6,582	6,976	7,217	7,259	7,301	8,447	9,576	12,799	15,407	17,727
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 56
Cumulative number of reported claims | claim	4,203
Insurance | Aviation | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,346	7,428	7,635	7,747	7,804	8,752	10,832	10,705	12,808
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 59
Cumulative number of reported claims | claim	2,859
Insurance | Aviation | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 16,700	16,793	15,502	15,615	15,278	15,234	16,349	15,657
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 149
Cumulative number of reported claims | claim	3,020
Insurance | Aviation | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 17,370	19,118	21,876	21,818	24,373	23,050	20,438
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 58
Cumulative number of reported claims | claim	3,534
Insurance | Aviation | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 28,038	27,557	29,613	29,877	28,534	29,796
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 86
Cumulative number of reported claims | claim	4,155
Insurance | Aviation | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 32,525	31,796	33,728	33,553	29,194
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 812
Cumulative number of reported claims | claim	4,091
Insurance | Aviation | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 70,029	67,644	62,643	56,102
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (1,046)
Cumulative number of reported claims | claim	4,347
Insurance | Aviation | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 62,696	64,250	58,340
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,262
Cumulative number of reported claims | claim	4,405
Insurance | Aviation | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 42,786	44,653
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 5,387
Cumulative number of reported claims | claim	2,785
Insurance | Aviation | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 37,092
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 22,625
Cumulative number of reported claims | claim	1,297
Insurance | Credit and political risk
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 354,068
Insurance | Credit and political risk | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	27,754	27,904	27,904	33,609	45,036	48,333	48,361	47,706	48,665	58,154
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 118
Cumulative number of reported claims | claim	4
Insurance | Credit and political risk | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 199	199	199	47	10,323	12,447	12,435	15,672	32,602
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 155
Cumulative number of reported claims | claim	4
Insurance | Credit and political risk | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 12,739	12,377	14,067	14,942	9,880	9,759	25,684	26,439
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 4,432
Cumulative number of reported claims | claim	2
Insurance | Credit and political risk | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 70,747	71,275	69,589	68,324	67,109	70,713	38,825
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,123
Cumulative number of reported claims | claim	6
Insurance | Credit and political risk | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 24,851	25,930	26,012	27,524	30,368	30,329
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,542
Cumulative number of reported claims | claim	2
Insurance | Credit and political risk | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 25,612	41,826	41,256	43,746	47,736
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,061
Cumulative number of reported claims | claim	1
Insurance | Credit and political risk | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 18,744	26,552	33,524	48,086
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 8,163
Cumulative number of reported claims | claim	3
Insurance | Credit and political risk | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 32,740	34,116	45,047
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,279
Cumulative number of reported claims | claim	1
Insurance | Credit and political risk | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 80,181	51,638
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 23,821
Cumulative number of reported claims | claim	14
Insurance | Credit and political risk | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 60,501
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 48,752
Cumulative number of reported claims | claim	24
Insurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 3,810,441
Insurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	345,862	351,191	353,862	353,336	344,964	331,903	327,971	335,265	316,639	314,835
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 22,156
Cumulative number of reported claims | claim	7,239
Insurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 335,671	353,860	355,893	367,369	365,291	377,895	378,793	377,296	330,010
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 22,818
Cumulative number of reported claims | claim	8,334
Insurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 340,078	336,933	358,938	356,643	367,072	400,434	399,136	385,460
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 41,955
Cumulative number of reported claims | claim	9,457
Insurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 350,182	356,930	374,397	394,748	423,998	413,840	414,720
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 63,136
Cumulative number of reported claims | claim	9,825
Insurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 329,502	346,488	359,619	384,477	379,036	379,378
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 54,530
Cumulative number of reported claims | claim	10,493
Insurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 372,198	361,799	360,116	353,679	351,055
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 76,612
Cumulative number of reported claims | claim	11,836
Insurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 435,827	439,134	403,257	396,543
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 154,318
Cumulative number of reported claims | claim	13,670
Insurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 432,338	378,822	365,577
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 196,909
Cumulative number of reported claims | claim	16,453
Insurance | Professional lines | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 429,729	407,043
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 248,218
Cumulative number of reported claims | claim	16,369
Insurance | Professional lines | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 439,054
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 384,984
Cumulative number of reported claims | claim	9,284
Insurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 1,490,684
Insurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	85,085	85,037	82,658	82,313	84,079	85,792	87,771	83,925	75,329	72,584
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,780
Cumulative number of reported claims | claim	3,691
Insurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 64,543	67,239	72,728	75,698	68,659	71,475	74,136	71,711	70,883
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 14,803
Cumulative number of reported claims | claim	3,312
Insurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 89,908	91,949	95,989	93,688	88,248	95,181	95,315	93,238
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 11,899
Cumulative number of reported claims | claim	3,693
Insurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 132,596	131,490	132,034	130,688	129,828	124,368	107,161
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 18,701
Cumulative number of reported claims | claim	5,087
Insurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 188,296	182,959	165,202	137,718	127,423	128,438
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 34,876
Cumulative number of reported claims | claim	6,351
Insurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 120,442	127,691	129,069	130,249	124,331
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 36,430
Cumulative number of reported claims | claim	7,262
Insurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 200,362	183,746	167,673	167,648
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 47,636
Cumulative number of reported claims | claim	8,542
Insurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 190,741	167,564	169,557
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 78,563
Cumulative number of reported claims | claim	8,255
Insurance | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 193,686	192,320
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 109,765
Cumulative number of reported claims | claim	7,119
Insurance | Liability | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 225,025
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 204,825
Cumulative number of reported claims | claim	3,977
Reinsurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,608,090
Reinsurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,068,938	1,072,109	1,070,875	1,069,295	1,070,969	1,096,469	1,113,395	1,156,008	1,156,022	1,147,558
Total of incurred-but-not-reported liabilities plus expected development on reported claims	4,016
Reinsurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	457,372	457,777	461,000	459,625	464,567	480,467	511,157	526,700	558,114
Total of incurred-but-not-reported liabilities plus expected development on reported claims	747
Reinsurance | Property and other | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	505,548	506,213	509,582	510,134	516,164	536,423	567,292	583,687
Total of incurred-but-not-reported liabilities plus expected development on reported claims	738
Reinsurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	521,230	524,099	524,785	526,767	539,285	565,279	544,212
Total of incurred-but-not-reported liabilities plus expected development on reported claims	39,729
Reinsurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	461,382	455,873	459,819	465,427	470,515	481,328
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,756
Reinsurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	628,910	626,868	630,447	644,393	623,624
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,351
Reinsurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,106,201	1,098,312	1,080,866	1,101,428
Total of incurred-but-not-reported liabilities plus expected development on reported claims	47,451
Reinsurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,025,683	1,020,689	889,102
Total of incurred-but-not-reported liabilities plus expected development on reported claims	68,161
Reinsurance | Property and other | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	977,194	966,716
Total of incurred-but-not-reported liabilities plus expected development on reported claims	183,064
Reinsurance | Property and other | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	855,632
Total of incurred-but-not-reported liabilities plus expected development on reported claims	442,418
Reinsurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,878,975
Reinsurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	163,620	167,553	178,046	201,175	209,133	209,993	212,362	203,632	202,548	202,330
Total of incurred-but-not-reported liabilities plus expected development on reported claims	8,396
Reinsurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	204,530	207,936	215,159	213,805	223,661	224,912	222,578	217,148	210,543
Total of incurred-but-not-reported liabilities plus expected development on reported claims	10,839
Reinsurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	170,614	183,035	207,425	214,668	215,064	216,716	215,431	210,173
Total of incurred-but-not-reported liabilities plus expected development on reported claims	17,670
Reinsurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	230,034	231,153	234,567	220,167	220,120	220,132	220,070
Total of incurred-but-not-reported liabilities plus expected development on reported claims	21,710
Reinsurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	230,331	233,056	226,092	215,362	213,076	212,683
Total of incurred-but-not-reported liabilities plus expected development on reported claims	37,004
Reinsurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	257,160	229,187	200,808	196,922	195,753
Total of incurred-but-not-reported liabilities plus expected development on reported claims	55,800
Reinsurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	180,501	163,474	157,025	156,074
Total of incurred-but-not-reported liabilities plus expected development on reported claims	64,159
Reinsurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	158,552	151,299	148,348
Total of incurred-but-not-reported liabilities plus expected development on reported claims	86,571
Reinsurance | Professional lines | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	142,176	141,702
Total of incurred-but-not-reported liabilities plus expected development on reported claims	101,309
Reinsurance | Professional lines | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	141,457
Total of incurred-but-not-reported liabilities plus expected development on reported claims	123,152
Reinsurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	2,310,074
Reinsurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	193,320	191,594	194,372	196,289	197,061	200,328	193,629	175,605	174,227	174,639
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,656
Reinsurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	161,267	159,163	165,296	172,431	175,105	173,932	169,091	164,844	168,766
Total of incurred-but-not-reported liabilities plus expected development on reported claims	10,642
Reinsurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	156,342	157,813	178,529	185,681	186,062	184,048	177,377	173,637
Total of incurred-but-not-reported liabilities plus expected development on reported claims	16,314
Reinsurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	189,296	199,173	201,313	202,487	206,463	204,684	201,352
Total of incurred-but-not-reported liabilities plus expected development on reported claims	28,929
Reinsurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	215,178	215,250	217,535	217,784	216,838	216,431
Total of incurred-but-not-reported liabilities plus expected development on reported claims	48,999
Reinsurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	267,235	256,767	253,506	248,194	242,579
Total of incurred-but-not-reported liabilities plus expected development on reported claims	73,124
Reinsurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	290,621	281,677	273,664	278,204
Total of incurred-but-not-reported liabilities plus expected development on reported claims	95,966
Reinsurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	277,824	272,102	267,162
Total of incurred-but-not-reported liabilities plus expected development on reported claims	127,342
Reinsurance | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	275,090	265,317
Total of incurred-but-not-reported liabilities plus expected development on reported claims	186,427
Reinsurance | Liability | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	283,901
Total of incurred-but-not-reported liabilities plus expected development on reported claims	239,574
Reinsurance | Credit and surety
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,143,639
Reinsurance | Credit and surety | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	100,503	102,612	105,776	106,414	108,220	117,020	119,067	111,684	113,314	124,676
Total of incurred-but-not-reported liabilities plus expected development on reported claims	1,102
Reinsurance | Credit and surety | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	127,775	130,049	133,199	136,944	145,254	153,928	156,952	154,131	164,496
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,141
Reinsurance | Credit and surety | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	131,791	128,982	128,951	140,569	145,059	149,059	158,105	168,742
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,600
Reinsurance | Credit and surety | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	126,854	130,638	132,014	143,931	147,688	140,462	139,551
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3,602
Reinsurance | Credit and surety | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	143,946	142,908	162,359	166,901	172,064	164,357
Total of incurred-but-not-reported liabilities plus expected development on reported claims	4,697
Reinsurance | Credit and surety | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	119,640	127,556	153,816	145,838	145,370
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3,335
Reinsurance | Credit and surety | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	122,789	131,559	137,372	142,334
Total of incurred-but-not-reported liabilities plus expected development on reported claims	4,399
Reinsurance | Credit and surety | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	120,639	125,256	114,691
Total of incurred-but-not-reported liabilities plus expected development on reported claims	30,189
Reinsurance | Credit and surety | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	72,559	77,203
Total of incurred-but-not-reported liabilities plus expected development on reported claims	17,807
Reinsurance | Credit and surety | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	77,143
Total of incurred-but-not-reported liabilities plus expected development on reported claims	39,026
Reinsurance | Motor
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	2,407,463
Reinsurance | Motor | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	139,182	142,017	150,105	155,648	166,869	176,048	179,943	173,561	169,341	$ 164,847
Total of incurred-but-not-reported liabilities plus expected development on reported claims	17,768
Reinsurance | Motor | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	131,937	131,573	140,251	143,492	153,524	158,734	166,747	179,151	$ 188,256
Total of incurred-but-not-reported liabilities plus expected development on reported claims	13,920
Reinsurance | Motor | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	129,238	132,624	141,827	145,148	148,804	158,838	171,275	$ 172,316
Total of incurred-but-not-reported liabilities plus expected development on reported claims	12,486
Reinsurance | Motor | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	175,871	179,646	183,197	187,883	191,121	196,133	$ 192,457
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,713
Reinsurance | Motor | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	223,532	225,413	237,299	235,796	231,712	$ 233,605
Total of incurred-but-not-reported liabilities plus expected development on reported claims	11,590
Reinsurance | Motor | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	261,473	270,554	281,659	279,115	$ 257,429
Total of incurred-but-not-reported liabilities plus expected development on reported claims	11,999
Reinsurance | Motor | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	378,976	377,292	396,370	$ 379,810
Total of incurred-but-not-reported liabilities plus expected development on reported claims	37,506
Reinsurance | Motor | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	391,410	378,515	$ 375,513
Total of incurred-but-not-reported liabilities plus expected development on reported claims	55,538
Reinsurance | Motor | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	354,568	$ 354,221
Total of incurred-but-not-reported liabilities plus expected development on reported claims	79,778
Reinsurance | Motor | Accident Year 2020
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	221,276
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 152,472

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