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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, 2019 USD ($) claim	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)
Insurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 3,945,377
Insurance | Property and other | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	114,355	$ 114,614	$ 115,712	$ 116,172	$ 116,477	$ 117,406	$ 122,897	$ 148,126	$ 155,512	$ 173,118
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 684
Cumulative number of reported claims | claim	4,423
Insurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 280,491	281,389	283,096	282,663	283,852	286,896	307,305	327,787	348,001
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ (18)
Cumulative number of reported claims | claim	6,350
Insurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 342,017	352,048	352,879	358,598	363,171	383,228	400,995	391,031
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 497
Cumulative number of reported claims | claim	29,931
Insurance | Property and other | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 275,074	278,790	268,350	268,704	272,642	299,498	309,937
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,505
Cumulative number of reported claims | claim	53,191
Insurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 326,638	328,252	329,251	344,878	355,495	360,874
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,990
Cumulative number of reported claims | claim	62,356
Insurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 252,560	255,392	259,725	270,793	278,554
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 4,077
Cumulative number of reported claims | claim	48,424
Insurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 356,353	369,508	377,820	351,075
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 6,011
Cumulative number of reported claims | claim	93,717
Insurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 808,602	829,016	885,486
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,992
Cumulative number of reported claims | claim	697,983
Insurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 759,300	721,266
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 41,900
Cumulative number of reported claims | claim	705,592
Insurance | Property and other | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 429,987
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 113,754
Cumulative number of reported claims | claim	445,460
Insurance | Marine
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 1,020,047
Insurance | Marine | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	44,696	45,064	45,482	47,226	48,618	51,482	53,458	66,359	70,314	68,519
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 262
Cumulative number of reported claims | claim	3,197
Insurance | Marine | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 68,330	69,011	68,318	66,156	65,921	65,973	72,875	78,807	90,776
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 976
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	$ 62,447	73,002	74,797	72,238	71,211	69,075	83,138	89,712
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,718
Cumulative number of reported claims | claim	4,134
Insurance | Marine | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 81,070	82,073	82,487	97,250	96,164	100,757	79,578
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,174
Cumulative number of reported claims | claim	2,353
Insurance | Marine | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 47,574	46,030	44,420	48,586	44,576	59,686
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 4,249
Cumulative number of reported claims | claim	2,163
Insurance | Marine | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 117,587	129,914	137,180	141,317	160,063
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,079
Cumulative number of reported claims | claim	2,228
Insurance | Marine | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 71,161	76,511	78,762	86,386
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 4,020
Cumulative number of reported claims | claim	2,841
Insurance | Marine | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 166,796	170,775	173,222
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 27,726
Cumulative number of reported claims | claim	3,976
Insurance | Marine | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 191,005	182,232
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 45,347
Cumulative number of reported claims | claim	4,232
Insurance | Marine | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 169,381
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 94,818
Cumulative number of reported claims | claim	3,525
Insurance | Aviation
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 291,275
Insurance | Aviation | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	8,836	8,868	8,525	8,741	8,695	8,766	9,745	11,420	11,698	12,917
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 48
Cumulative number of reported claims | claim	663
Insurance | Aviation | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 6,952	7,192	7,234	7,277	8,424	9,555	12,781	15,391	17,724
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 118
Cumulative number of reported claims | claim	4,202
Insurance | Aviation | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,392	7,599	7,712	7,769	8,718	10,801	10,677	12,793
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 83
Cumulative number of reported claims | claim	2,857
Insurance | Aviation | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 16,763	15,470	15,585	15,249	15,205	16,330	15,652
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 255
Cumulative number of reported claims | claim	3,017
Insurance | Aviation | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 19,088	21,847	21,789	24,349	23,033	20,435
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 493
Cumulative number of reported claims | claim	3,529
Insurance | Aviation | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 27,512	29,567	29,833	28,502	29,782
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 299
Cumulative number of reported claims | claim	4,140
Insurance | Aviation | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 31,723	33,658	33,502	29,173
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 606
Cumulative number of reported claims | claim	4,062
Insurance | Aviation | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 66,896	62,035	55,581
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,747
Cumulative number of reported claims | claim	4,272
Insurance | Aviation | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 63,753	57,990
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 6,841
Cumulative number of reported claims | claim	4,258
Insurance | Aviation | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 42,360
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 11,632
Cumulative number of reported claims | claim	2,305
Insurance | Credit and political risk
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 395,724
Insurance | Credit and political risk | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	99,633	99,423	90,888	72,104	65,014	64,980	65,597	63,259	63,179	62,415
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 339
Cumulative number of reported claims | claim	6
Insurance | Credit and political risk | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 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	$ 268
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	$ 198	198	46	10,322	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	$ 12,377	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	$ 4,070
Cumulative number of reported claims | claim	1
Insurance | Credit and political risk | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 71,274	69,589	68,324	67,109	70,713	38,825
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,822
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	$ 25,930	26,012	27,524	30,368	30,329
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,621
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	$ 42,972	42,401	44,891	45,391
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 18,275
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	$ 28,209	34,765	36,751
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 17,808
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	$ 36,618	47,215
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,576
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	$ 50,609
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 33,702
Cumulative number of reported claims | claim	5
Insurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 3,490,705
Insurance | Professional lines | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	185,116	187,464	167,917	180,704	158,729	183,237	206,406	234,655	237,156	232,002
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 17,194
Cumulative number of reported claims | claim	5,698
Insurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 350,066	352,792	352,309	343,911	330,773	326,663	333,914	315,326	313,520
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 28,007
Cumulative number of reported claims | claim	7,229
Insurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 351,283	353,182	364,443	362,534	375,549	376,603	375,164	328,397
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 34,964
Cumulative number of reported claims | claim	8,326
Insurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 334,398	356,261	354,190	364,851	398,059	396,819	383,432
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 49,144
Cumulative number of reported claims | claim	9,439
Insurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 353,994	371,407	391,952	421,093	411,232	412,523
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 76,580
Cumulative number of reported claims | claim	9,802
Insurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 344,239	357,646	382,679	376,865	377,129
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 87,707
Cumulative number of reported claims | claim	10,453
Insurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 359,813	358,368	351,990	349,030
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 105,971
Cumulative number of reported claims | claim	11,763
Insurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 437,528	397,760	378,746
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 197,748
Cumulative number of reported claims | claim	13,418
Insurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 374,683	361,490
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 217,867
Cumulative number of reported claims | claim	15,584
Insurance | Professional lines | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 399,585
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 348,212
Cumulative number of reported claims | claim	11,747
Insurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 1,336,252
Insurance | Liability | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	107,420	104,042	104,465	105,438	98,529	100,133	98,853	98,642	94,222	79,398
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,287
Cumulative number of reported claims | claim	4,029
Insurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 85,036	82,657	82,312	84,079	85,792	87,770	83,925	75,329	72,580
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 14,042
Cumulative number of reported claims | claim	3,571
Insurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 67,237	72,727	75,697	68,658	71,474	74,134	71,683	70,887
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 18,015
Cumulative number of reported claims | claim	3,188
Insurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 91,941	95,981	93,681	88,241	95,174	95,306	93,233
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 16,997
Cumulative number of reported claims | claim	3,568
Insurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 131,474	132,019	130,672	129,764	124,303	107,133
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 22,710
Cumulative number of reported claims | claim	4,865
Insurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 183,088	165,073	137,568	127,353	128,437
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 43,822
Cumulative number of reported claims | claim	6,225
Insurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 127,528	128,911	130,188	124,323
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 53,401
Cumulative number of reported claims | claim	7,068
Insurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 183,793	166,573	162,446
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 76,834
Cumulative number of reported claims | claim	6,710
Insurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 167,614	168,146
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 95,288
Cumulative number of reported claims | claim	5,454
Insurance | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 191,121
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 165,431
Cumulative number of reported claims | claim	3,714
Reinsurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,226,127
Reinsurance | Property and other | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	566,112	567,879	568,725	570,796	578,740	584,942	581,838	570,057	601,243	614,748
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3,070
Reinsurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,041,771	1,040,759	1,039,379	1,041,136	1,067,100	1,084,197	1,116,042	1,116,669	1,111,563
Total of incurred-but-not-reported liabilities plus expected development on reported claims	7,782
Reinsurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	454,281	457,531	456,127	461,152	476,989	507,619	523,208	555,459
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,860
Reinsurance | Property and other | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	499,736	503,026	503,539	509,526	529,856	560,658	578,725
Total of incurred-but-not-reported liabilities plus expected development on reported claims	1,904
Reinsurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	519,529	520,299	522,102	534,618	560,775	542,601
Total of incurred-but-not-reported liabilities plus expected development on reported claims	40,234
Reinsurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	450,182	454,225	459,487	464,588	477,301
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,030
Reinsurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	618,643	622,331	635,164	616,621
Total of incurred-but-not-reported liabilities plus expected development on reported claims	11,017
Reinsurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,107,597	1,081,415	1,076,967
Total of incurred-but-not-reported liabilities plus expected development on reported claims	75,459
Reinsurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,008,505	882,829
Total of incurred-but-not-reported liabilities plus expected development on reported claims	166,887
Reinsurance | Property and other | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	959,771
Total of incurred-but-not-reported liabilities plus expected development on reported claims	729,042
Reinsurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,862,842
Reinsurance | Professional lines | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	167,376	166,044	179,762	189,415	196,939	214,185	214,417	211,361	210,173	209,934
Total of incurred-but-not-reported liabilities plus expected development on reported claims	5,701
Reinsurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	166,951	177,405	200,437	208,219	209,088	211,367	202,620	201,364	201,013
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,047
Reinsurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	206,791	213,984	212,594	222,626	223,926	221,544	216,088	209,548
Total of incurred-but-not-reported liabilities plus expected development on reported claims	18,318
Reinsurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	181,563	205,733	213,182	213,745	215,562	214,396	209,292
Total of incurred-but-not-reported liabilities plus expected development on reported claims	35,871
Reinsurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	230,042	233,611	219,242	219,345	219,415	219,376
Total of incurred-but-not-reported liabilities plus expected development on reported claims	27,940
Reinsurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	231,980	225,139	214,344	212,024	212,031
Total of incurred-but-not-reported liabilities plus expected development on reported claims	63,050
Reinsurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	227,952	200,020	196,293	195,190
Total of incurred-but-not-reported liabilities plus expected development on reported claims	67,496
Reinsurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	162,116	155,759	155,137
Total of incurred-but-not-reported liabilities plus expected development on reported claims	72,727
Reinsurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	148,921	146,387
Total of incurred-but-not-reported liabilities plus expected development on reported claims	132,683
Reinsurance | Professional lines | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	139,150
Total of incurred-but-not-reported liabilities plus expected development on reported claims	130,571
Reinsurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	2,136,911
Reinsurance | Liability | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	156,113	159,230	165,983	181,962	190,921	202,007	183,715	183,347	171,775	172,823
Total of incurred-but-not-reported liabilities plus expected development on reported claims	13,119
Reinsurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	189,014	191,873	193,784	194,604	197,766	191,668	173,984	172,201	172,189
Total of incurred-but-not-reported liabilities plus expected development on reported claims	16,614
Reinsurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	158,342	164,309	170,979	173,501	172,341	167,366	162,945	166,386
Total of incurred-but-not-reported liabilities plus expected development on reported claims	16,994
Reinsurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	157,236	177,112	183,915	184,240	182,201	175,174	171,271
Total of incurred-but-not-reported liabilities plus expected development on reported claims	24,545
Reinsurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	197,187	199,340	200,557	204,657	202,939	199,433
Total of incurred-but-not-reported liabilities plus expected development on reported claims	53,905
Reinsurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	213,662	215,889	216,061	215,099	214,735
Total of incurred-but-not-reported liabilities plus expected development on reported claims	67,030
Reinsurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	254,154	250,868	245,820	240,440
Total of incurred-but-not-reported liabilities plus expected development on reported claims	99,784
Reinsurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	279,172	270,589	276,929
Total of incurred-but-not-reported liabilities plus expected development on reported claims	133,392
Reinsurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	268,506	264,570
Total of incurred-but-not-reported liabilities plus expected development on reported claims	168,425
Reinsurance | Liability | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	263,525
Total of incurred-but-not-reported liabilities plus expected development on reported claims	214,542
Reinsurance | Credit and surety
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,126,325
Reinsurance | Credit and surety | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	71,911	73,672	74,913	76,937	78,247	85,856	90,029	92,848	99,460	119,180
Total of incurred-but-not-reported liabilities plus expected development on reported claims	1,751
Reinsurance | Credit and surety | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	95,813	98,885	99,412	101,236	109,662	111,485	104,616	106,495	120,572
Total of incurred-but-not-reported liabilities plus expected development on reported claims	2,439
Reinsurance | Credit and surety | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	124,552	127,576	131,120	139,097	147,406	150,137	147,627	159,507
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3,883
Reinsurance | Credit and surety | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	124,674	124,533	135,762	139,886	143,719	152,467	164,207
Total of incurred-but-not-reported liabilities plus expected development on reported claims	3,546
Reinsurance | Credit and surety | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	126,397	127,683	139,015	142,703	135,525	136,419
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,726
Reinsurance | Credit and surety | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	137,848	156,635	160,675	165,861	160,132
Total of incurred-but-not-reported liabilities plus expected development on reported claims	8,335
Reinsurance | Credit and surety | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	123,366	148,943	141,128	141,639
Total of incurred-but-not-reported liabilities plus expected development on reported claims	9,849
Reinsurance | Credit and surety | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	126,786	132,618	135,040
Total of incurred-but-not-reported liabilities plus expected development on reported claims	22,830
Reinsurance | Credit and surety | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	120,289	111,692
Total of incurred-but-not-reported liabilities plus expected development on reported claims	38,357
Reinsurance | Credit and surety | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	74,689
Total of incurred-but-not-reported liabilities plus expected development on reported claims	39,291
Reinsurance | Motor
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	2,182,564
Reinsurance | Motor | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	80,028	80,901	83,112	86,803	96,235	101,343	107,264	108,183	107,538	$ 100,219
Total of incurred-but-not-reported liabilities plus expected development on reported claims	21,660
Reinsurance | Motor | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	136,077	143,846	148,536	159,626	168,225	172,062	166,112	162,069	$ 158,475
Total of incurred-but-not-reported liabilities plus expected development on reported claims	18,030
Reinsurance | Motor | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	126,507	134,685	137,585	147,041	151,899	159,446	170,848	$ 180,137
Total of incurred-but-not-reported liabilities plus expected development on reported claims	15,534
Reinsurance | Motor | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	126,050	135,003	137,791	141,237	150,620	162,475	$ 164,927
Total of incurred-but-not-reported liabilities plus expected development on reported claims	13,828
Reinsurance | Motor | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	171,403	174,719	179,510	182,237	186,947	$ 185,279
Total of incurred-but-not-reported liabilities plus expected development on reported claims	6,302
Reinsurance | Motor | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	216,610	227,844	226,319	222,178	$ 225,974
Total of incurred-but-not-reported liabilities plus expected development on reported claims	12,291
Reinsurance | Motor | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	259,959	270,264	268,525	$ 249,616
Total of incurred-but-not-reported liabilities plus expected development on reported claims	21,855
Reinsurance | Motor | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	362,721	380,509	$ 370,778
Total of incurred-but-not-reported liabilities plus expected development on reported claims	50,597
Reinsurance | Motor | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	363,733	$ 363,917
Total of incurred-but-not-reported liabilities plus expected development on reported claims	83,024
Reinsurance | Motor | Accident Year 2019
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	339,476
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 165,127

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