RESERVE FOR LOSSES AND LOSS EXPENSES - Incurred claims and allocated claim adjustment expenses, net of reinsurance (Details) $ in Thousands	Dec. 31, 2018 USD ($) claim	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)	Dec. 31, 2012 USD ($)	Dec. 31, 2011 USD ($)	Dec. 31, 2010 USD ($)	Dec. 31, 2009 USD ($)
Insurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 3,583,317
Insurance | Property and other | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	77,338	$ 78,395	$ 78,150	$ 78,490	$ 78,269	$ 80,461	$ 82,460	$ 89,768	$ 99,079	$ 117,309
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 83
Cumulative number of reported claims | claim	3,201
Insurance | Property and other | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 113,767	114,866	115,316	115,635	116,562	122,111	147,426	155,032	175,012
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 867
Cumulative number of reported claims | claim	4,422
Insurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 279,996	281,866	281,405	282,755	285,745	306,114	338,220	359,132
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 979
Cumulative number of reported claims | claim	6,348
Insurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 350,827	351,673	357,267	361,476	381,746	399,473	391,646
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 8,992
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	$ 276,940	266,727	267,022	271,157	297,713	308,359
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 6,687
Cumulative number of reported claims | claim	53,172
Insurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 326,100	327,389	343,333	354,219	360,130
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 5,917
Cumulative number of reported claims | claim	62,444
Insurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 253,729	257,927	268,897	277,332
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 5,642
Cumulative number of reported claims | claim	47,052
Insurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 367,362	376,458	349,152
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,290
Cumulative number of reported claims | claim	92,867
Insurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 825,176	882,968
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 42,188
Cumulative number of reported claims | claim	663,914
Insurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 712,082
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 187,391
Cumulative number of reported claims | claim	730,832
Insurance | Marine
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 920,554
Insurance | Marine | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	50,735	52,283	52,400	53,514	54,906	57,106	64,477	69,862	74,181	80,615
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 359
Cumulative number of reported claims | claim	3,220
Insurance | Marine | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 45,125	45,543	47,249	48,650	51,483	53,388	66,389	70,394	68,528
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 643
Cumulative number of reported claims | claim	3,196
Insurance | Marine | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 68,829	68,140	65,983	65,769	65,766	72,530	78,700	90,717
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,005
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	$ 72,585	74,445	71,823	70,855	68,715	82,648	89,639
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,055
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	$ 82,136	82,547	97,265	96,210	100,767	79,610
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,729
Cumulative number of reported claims | claim	2,351
Insurance | Marine | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 45,980	44,392	48,481	44,463	59,558
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 5,454
Cumulative number of reported claims | claim	2,157
Insurance | Marine | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 129,627	136,827	140,050	158,755
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 8,498
Cumulative number of reported claims | claim	2,219
Insurance | Marine | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 76,743	78,779	86,264
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,819
Cumulative number of reported claims | claim	2,795
Insurance | Marine | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 170,085	171,936
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 49,990
Cumulative number of reported claims | claim	3,863
Insurance | Marine | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 178,709
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 113,414
Cumulative number of reported claims | claim	3,250
Insurance | Aviation
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 261,202
Insurance | Aviation | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	13,821	14,330	14,604	15,437	16,618	16,743	18,090	18,752	14,560	17,468
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 41
Cumulative number of reported claims | claim	1,659
Insurance | Aviation | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 8,900	8,548	8,744	8,699	8,769	9,749	11,422	11,699	12,922
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 78
Cumulative number of reported claims | claim	1,950
Insurance | Aviation | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,203	7,242	7,275	8,422	9,552	12,779	15,390	17,723
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 205
Cumulative number of reported claims | claim	2,145
Insurance | Aviation | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 7,695	7,804	7,758	8,708	10,791	10,668	12,789
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 200
Cumulative number of reported claims | claim	2,242
Insurance | Aviation | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 15,502	15,618	15,243	15,199	16,327	15,651
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 292
Cumulative number of reported claims | claim	2,320
Insurance | Aviation | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 22,183	22,104	24,339	23,028	20,432
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 425
Cumulative number of reported claims | claim	2,717
Insurance | Aviation | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 30,135	30,363	28,479	29,761
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,480
Cumulative number of reported claims | claim	3,484
Insurance | Aviation | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 34,513	34,328	29,154
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,845
Cumulative number of reported claims | claim	3,456
Insurance | Aviation | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 63,295	56,565
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 7,676
Cumulative number of reported claims | claim	3,452
Insurance | Aviation | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 57,955
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 12,452
Cumulative number of reported claims | claim	2,280
Insurance | Credit and political risk
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 700,799
Insurance | Credit and political risk | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	340,648	339,534	339,570	335,291	335,271	334,965	335,536	326,024	305,282	248,083
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 3,600
Cumulative number of reported claims | claim	24
Insurance | Credit and political risk | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 99,416	90,880	72,101	65,011	64,977	65,596	63,259	63,179	62,415
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,316
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	$ 27,899	33,604	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	$ 197	44	10,320	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	$ 14,065	14,941	9,880	9,759	25,684	26,439
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 5,759
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	$ 69,586	68,320	67,109	70,712	38,825
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 1,136
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	$ 26,001	27,513	30,368	30,329
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 2,703
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	$ 42,184	44,639	45,907
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 17,704
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	$ 34,631	36,563
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 28,083
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	$ 46,172
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 33,079
Cumulative number of reported claims | claim	1
Insurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 3,298,346
Insurance | Professional lines | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	224,778	220,524	212,994	236,751	236,657	253,979	244,466	243,978	243,522	240,092
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 13,640
Cumulative number of reported claims | claim	5,889
Insurance | Professional lines | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 186,340	167,038	179,517	157,921	181,917	204,744	233,407	235,610	230,353
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 18,897
Cumulative number of reported claims | claim	5,690
Insurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 351,747	351,247	342,598	329,318	324,739	331,800	314,466	312,805
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 33,877
Cumulative number of reported claims | claim	7,215
Insurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 351,498	362,606	360,596	373,306	374,315	372,782	327,590
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 50,067
Cumulative number of reported claims | claim	8,300
Insurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 353,112	351,330	361,785	394,461	394,548	382,270
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 70,914
Cumulative number of reported claims | claim	9,409
Insurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 369,129	389,610	418,164	407,688	408,103
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 111,975
Cumulative number of reported claims | claim	9,766
Insurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 355,300	380,265	373,747	374,209
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 127,537
Cumulative number of reported claims | claim	10,379
Insurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 355,601	349,223	346,289
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 152,080
Cumulative number of reported claims | claim	11,632
Insurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 393,443	375,397
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 256,260
Cumulative number of reported claims | claim	12,903
Insurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 357,398
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 304,926
Cumulative number of reported claims | claim	12,392
Insurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 1,208,108
Insurance | Liability | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	97,964	98,999	98,384	101,179	83,281	75,883	67,869	67,410	64,017	61,469
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 9,450
Cumulative number of reported claims | claim	4,093
Insurance | Liability | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 103,906	104,258	105,119	98,061	99,570	98,112	98,635	94,220	79,407
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 11,742
Cumulative number of reported claims | claim	3,670
Insurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 82,625	82,127	83,730	85,242	87,059	83,118	75,329	72,586
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 17,357
Cumulative number of reported claims | claim	3,222
Insurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 72,514	75,341	68,180	70,770	73,281	70,631	70,861
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 23,236
Cumulative number of reported claims | claim	2,837
Insurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 95,632	93,216	87,498	94,253	94,178	92,150
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 21,345
Cumulative number of reported claims | claim	3,520
Insurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 131,539	130,021	128,524	122,643	106,148
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 31,126
Cumulative number of reported claims | claim	4,614
Insurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 164,036	136,305	125,819	127,319
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 52,818
Cumulative number of reported claims | claim	5,975
Insurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 128,172	129,139	123,243
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 73,747
Cumulative number of reported claims | claim	6,628
Insurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 165,061	161,211
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 107,070
Cumulative number of reported claims | claim	5,842
Insurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 166,659
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 141,099
Cumulative number of reported claims | claim	3,725
Reinsurance | Property and other
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	$ 6,321,728
Reinsurance | Property and other | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	198,189	197,779	200,422	198,498	204,560	223,245	232,639	246,047	284,210	340,527
Total of incurred-but-not-reported liabilities plus expected development on reported claims	1,722
Reinsurance | Property and other | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	568,179	569,043	571,120	579,065	585,247	582,855	569,357	600,219	612,614
Total of incurred-but-not-reported liabilities plus expected development on reported claims	5,532
Reinsurance | Property and other | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,040,130	1,038,726	1,040,470	1,066,384	1,083,492	1,124,792	1,116,708	1,109,682
Total of incurred-but-not-reported liabilities plus expected development on reported claims	10,579
Reinsurance | Property and other | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	457,703	456,334	461,255	477,145	507,750	523,310	555,241
Total of incurred-but-not-reported liabilities plus expected development on reported claims	8,446
Reinsurance | Property and other | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	502,642	503,203	509,179	529,463	560,227	578,645
Total of incurred-but-not-reported liabilities plus expected development on reported claims	5,140
Reinsurance | Property and other | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	519,967	521,797	534,229	560,478	540,406
Total of incurred-but-not-reported liabilities plus expected development on reported claims	43,358
Reinsurance | Property and other | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	453,628	459,017	463,996	477,608
Total of incurred-but-not-reported liabilities plus expected development on reported claims	14,117
Reinsurance | Property and other | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	620,702	633,597	614,940
Total of incurred-but-not-reported liabilities plus expected development on reported claims	30,481
Reinsurance | Property and other | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,080,319	1,076,458
Total of incurred-but-not-reported liabilities plus expected development on reported claims	123,562
Reinsurance | Property and other | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	880,269
Total of incurred-but-not-reported liabilities plus expected development on reported claims	492,589
Reinsurance | Professional lines
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,903,167
Reinsurance | Professional lines | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	179,945	180,862	189,991	193,803	208,693	208,338	218,469	215,827	211,191	211,420
Total of incurred-but-not-reported liabilities plus expected development on reported claims	4,495
Reinsurance | Professional lines | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	165,864	179,604	189,263	196,770	214,161	214,439	211,409	210,238	210,016
Total of incurred-but-not-reported liabilities plus expected development on reported claims	10,034
Reinsurance | Professional lines | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	177,163	200,168	207,946	208,828	211,459	202,815	201,735	201,457
Total of incurred-but-not-reported liabilities plus expected development on reported claims	22,132
Reinsurance | Professional lines | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	213,850	212,485	222,499	223,813	221,808	216,415	209,889
Total of incurred-but-not-reported liabilities plus expected development on reported claims	33,873
Reinsurance | Professional lines | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	205,586	213,142	213,765	215,544	214,624	209,538
Total of incurred-but-not-reported liabilities plus expected development on reported claims	67,043
Reinsurance | Professional lines | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	233,427	219,109	219,286	219,332	219,378
Total of incurred-but-not-reported liabilities plus expected development on reported claims	48,605
Reinsurance | Professional lines | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	225,003	214,310	212,150	212,030
Total of incurred-but-not-reported liabilities plus expected development on reported claims	84,299
Reinsurance | Professional lines | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	199,879	196,246	195,061
Total of incurred-but-not-reported liabilities plus expected development on reported claims	84,621
Reinsurance | Professional lines | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	155,892	155,211
Total of incurred-but-not-reported liabilities plus expected development on reported claims	109,070
Reinsurance | Professional lines | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	146,558
Total of incurred-but-not-reported liabilities plus expected development on reported claims	142,282
Reinsurance | Credit and surety
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,201,632
Reinsurance | Credit and surety | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	92,519	93,688	95,321	95,726	98,958	104,236	105,062	105,827	122,111	143,398
Total of incurred-but-not-reported liabilities plus expected development on reported claims	1,304
Reinsurance | Credit and surety | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	74,430	75,716	77,732	79,047	86,528	90,657	93,548	100,047	119,152
Total of incurred-but-not-reported liabilities plus expected development on reported claims	4,092
Reinsurance | Credit and surety | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	100,146	100,718	102,529	111,019	112,964	105,955	107,811	121,471
Total of incurred-but-not-reported liabilities plus expected development on reported claims	5,770
Reinsurance | Credit and surety | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	128,323	131,963	140,000	148,363	151,141	148,566	160,109
Total of incurred-but-not-reported liabilities plus expected development on reported claims	8,830
Reinsurance | Credit and surety | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	125,112	136,402	140,589	144,472	153,616	165,413
Total of incurred-but-not-reported liabilities plus expected development on reported claims	8,083
Reinsurance | Credit and surety | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	128,404	139,857	143,515	136,346	135,732
Total of incurred-but-not-reported liabilities plus expected development on reported claims	11,280
Reinsurance | Credit and surety | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	157,612	161,789	166,951	160,837
Total of incurred-but-not-reported liabilities plus expected development on reported claims	26,891
Reinsurance | Credit and surety | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	149,054	141,780	142,245
Total of incurred-but-not-reported liabilities plus expected development on reported claims	38,746
Reinsurance | Credit and surety | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	134,063	135,750
Total of incurred-but-not-reported liabilities plus expected development on reported claims	38,299
Reinsurance | Credit and surety | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	111,969
Total of incurred-but-not-reported liabilities plus expected development on reported claims	53,762
Reinsurance | Motor
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	1,942,568
Reinsurance | Motor | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	77,829	80,204	77,943	83,517	92,158	90,860	89,057	87,140	79,515	81,369
Total of incurred-but-not-reported liabilities plus expected development on reported claims	17,628
Reinsurance | Motor | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	78,575	81,228	84,535	93,919	99,061	104,993	106,092	105,669	98,704
Total of incurred-but-not-reported liabilities plus expected development on reported claims	19,993
Reinsurance | Motor | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	140,191	145,482	155,948	164,559	168,436	162,586	158,750	156,069
Total of incurred-but-not-reported liabilities plus expected development on reported claims	24,417
Reinsurance | Motor | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	131,690	134,768	144,164	149,100	156,460	167,788	178,052
Total of incurred-but-not-reported liabilities plus expected development on reported claims	22,562
Reinsurance | Motor | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	131,081	134,200	137,695	147,139	158,632	162,681
Total of incurred-but-not-reported liabilities plus expected development on reported claims	21,880
Reinsurance | Motor | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	169,776	174,457	177,575	182,555	182,625
Total of incurred-but-not-reported liabilities plus expected development on reported claims	9,307
Reinsurance | Motor | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	221,982	220,527	216,808	222,768
Total of incurred-but-not-reported liabilities plus expected development on reported claims	29,755
Reinsurance | Motor | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	263,168	261,369	245,899
Total of incurred-but-not-reported liabilities plus expected development on reported claims	43,569
Reinsurance | Motor | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	371,089	363,651
Total of incurred-but-not-reported liabilities plus expected development on reported claims	84,007
Reinsurance | Motor | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	357,187
Total of incurred-but-not-reported liabilities plus expected development on reported claims	172,384
Reinsurance | Liability
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	2,070,199
Reinsurance | Liability | Accident Year 2009
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	175,770	168,917	178,260	192,287	204,531	184,811	178,149	180,945	174,121	$ 172,680
Total of incurred-but-not-reported liabilities plus expected development on reported claims	13,563
Reinsurance | Liability | Accident Year 2010
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	159,156	165,990	181,938	190,959	201,329	183,056	182,515	170,784	$ 171,634
Total of incurred-but-not-reported liabilities plus expected development on reported claims	14,137
Reinsurance | Liability | Accident Year 2011
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	191,962	193,830	194,715	197,871	191,761	174,124	172,399	$ 172,431
Total of incurred-but-not-reported liabilities plus expected development on reported claims	24,450
Reinsurance | Liability | Accident Year 2012
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	164,357	171,121	173,645	172,491	167,887	163,625	$ 167,290
Total of incurred-but-not-reported liabilities plus expected development on reported claims	27,789
Reinsurance | Liability | Accident Year 2013
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	177,273	184,147	184,467	182,428	176,465	$ 172,784
Total of incurred-but-not-reported liabilities plus expected development on reported claims	53,822
Reinsurance | Liability | Accident Year 2014
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	199,583	200,819	204,871	203,136	$ 200,203
Total of incurred-but-not-reported liabilities plus expected development on reported claims	75,626
Reinsurance | Liability | Accident Year 2015
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	215,997	216,201	215,273	$ 214,942
Total of incurred-but-not-reported liabilities plus expected development on reported claims	97,353
Reinsurance | Liability | Accident Year 2016
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	251,087	246,024	$ 240,411
Total of incurred-but-not-reported liabilities plus expected development on reported claims	131,475
Reinsurance | Liability | Accident Year 2017
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	270,564	$ 277,034
Total of incurred-but-not-reported liabilities plus expected development on reported claims	176,854
Reinsurance | Liability | Accident Year 2018
Claims Development [Line Items]
Incurred claims and allocated claim adjustment expenses, net of reinsurance	264,450
Total of incurred-but-not-reported liabilities plus expected development on reported claims	$ 209,612