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Short Duration Contracts - Claims development - Insurance (Details) $ in Thousands	Dec. 31, 2020 USD ($) claims	Dec. 31, 2019 USD ($)	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 ($)	Dec. 31, 2011 USD ($)
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for losses and loss adjustment expenses, net of reinsurance	$ 11,923,393
Insurance | Property, energy, marine and aviation
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,766,001
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	1,296,930
All outstanding liabilities before 2008, net of reinsurance	23,517
Liabilities for losses and loss adjustment expenses, net of reinsurance	492,588
Insurance | Property, energy, marine and aviation | 2011
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	196,436	$ 197,833	$ 201,198	$ 200,918	$ 207,814	$ 210,926	$ 220,231	$ 231,841	$ 272,897	$ 269,739
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	195,347	195,245	198,626	197,720	202,347	200,473	167,867	142,231	99,724	34,478
Total of IBNR liabilities plus expected development on reported claims	$ 689
Cumulative number of reported claims | claims	4,219
Insurance | Property, energy, marine and aviation | 2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 177,673	178,039	190,192	192,406	196,405	198,837	205,098	231,742	232,500
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	173,460	172,611	180,734	179,371	166,965	161,255	138,431	92,855	20,522
Total of IBNR liabilities plus expected development on reported claims	$ 931
Cumulative number of reported claims | claims	4,269
Insurance | Property, energy, marine and aviation | 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 126,968	128,301	133,544	134,620	143,046	148,800	156,344	158,718
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	124,369	123,036	125,156	121,922	119,791	110,548	84,759	32,239
Total of IBNR liabilities plus expected development on reported claims	$ 809
Cumulative number of reported claims | claims	4,278
Insurance | Property, energy, marine and aviation | 2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 134,937	134,234	132,209	136,096	147,315	145,765	148,185
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	115,293	98,463	87,721	84,103	77,804	53,669	25,859
Total of IBNR liabilities plus expected development on reported claims	$ 4,206
Cumulative number of reported claims | claims	3,930
Insurance | Property, energy, marine and aviation | 2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 91,788	97,809	102,469	103,944	109,799	112,333
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	86,207	87,887	86,214	76,299	64,916	23,567
Total of IBNR liabilities plus expected development on reported claims	$ 5,249
Cumulative number of reported claims | claims	4,618
Insurance | Property, energy, marine and aviation | 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 96,127	100,147	105,330	100,986	104,139
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	94,703	97,218	98,420	83,321	24,728
Total of IBNR liabilities plus expected development on reported claims	$ 882
Cumulative number of reported claims | claims	6,389
Insurance | Property, energy, marine and aviation | 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 230,421	235,932	246,272	280,695
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	211,694	195,518	139,854	30,219
Total of IBNR liabilities plus expected development on reported claims	$ 9,327
Cumulative number of reported claims | claims	6,752
Insurance | Property, energy, marine and aviation | 2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 173,693	186,030	180,981
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	134,858	102,285	30,026
Total of IBNR liabilities plus expected development on reported claims	$ 14,784
Cumulative number of reported claims | claims	5,347
Insurance | Property, energy, marine and aviation | 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 178,564	179,056
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	105,380	26,130
Total of IBNR liabilities plus expected development on reported claims	$ 20,553
Cumulative number of reported claims | claims	6,051
Insurance | Property, energy, marine and aviation | 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 359,394
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	55,619
Total of IBNR liabilities plus expected development on reported claims	$ 168,463
Cumulative number of reported claims | claims	16,980
Insurance | Third party occurrence business
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 3,802,970
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	1,453,716
All outstanding liabilities before 2008, net of reinsurance	209,031
Liabilities for losses and loss adjustment expenses, net of reinsurance	2,558,285
Insurance | Third party occurrence business | 2011
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	235,073	234,782	239,676	247,052	253,976	252,615	258,784	254,181	240,669	234,068
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	181,505	172,940	160,609	152,756	134,622	113,502	73,448	43,479	25,276	7,020
Total of IBNR liabilities plus expected development on reported claims	$ 35,138
Cumulative number of reported claims | claims	70,924
Insurance | Third party occurrence business | 2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 241,378	243,484	242,930	252,822	257,418	271,035	268,365	262,718	241,062
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	162,202	154,282	143,177	129,572	108,252	83,328	58,444	30,824	6,966
Total of IBNR liabilities plus expected development on reported claims	$ 50,208
Cumulative number of reported claims | claims	65,495
Insurance | Third party occurrence business | 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 269,437	272,528	274,391	281,786	301,789	306,751	296,839	282,968
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	174,700	164,187	149,098	122,120	101,196	71,370	29,230	6,845
Total of IBNR liabilities plus expected development on reported claims	$ 60,720
Cumulative number of reported claims | claims	66,685
Insurance | Third party occurrence business | 2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 342,731	343,995	339,495	342,868	338,623	335,720	329,809
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	211,503	191,168	161,993	112,591	71,519	40,263	9,209
Total of IBNR liabilities plus expected development on reported claims	$ 77,547
Cumulative number of reported claims | claims	74,964
Insurance | Third party occurrence business | 2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 382,518	391,231	391,904	398,670	391,666	358,858
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	211,573	181,566	139,403	88,443	44,542	11,119
Total of IBNR liabilities plus expected development on reported claims	$ 107,083
Cumulative number of reported claims | claims	77,257
Insurance | Third party occurrence business | 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 374,728	399,394	405,889	394,281	389,623
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	164,573	136,793	87,565	41,938	11,689
Total of IBNR liabilities plus expected development on reported claims	$ 142,000
Cumulative number of reported claims | claims	76,765
Insurance | Third party occurrence business | 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 412,318	422,441	417,748	417,183
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	135,025	99,827	52,323	13,396
Total of IBNR liabilities plus expected development on reported claims	$ 195,684
Cumulative number of reported claims | claims	82,267
Insurance | Third party occurrence business | 2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 450,736	452,975	430,216
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	115,076	63,798	17,002
Total of IBNR liabilities plus expected development on reported claims	$ 248,271
Cumulative number of reported claims | claims	74,789
Insurance | Third party occurrence business | 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 487,224	456,059
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	73,120	18,392
Total of IBNR liabilities plus expected development on reported claims	$ 318,622
Cumulative number of reported claims | claims	80,934
Insurance | Third party occurrence business | 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 606,827
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	24,439
Total of IBNR liabilities plus expected development on reported claims	$ 524,473
Cumulative number of reported claims | claims	67,541
Insurance | Third party claims-made business
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 3,042,469
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	1,763,247
All outstanding liabilities before 2008, net of reinsurance	97,957
Liabilities for losses and loss adjustment expenses, net of reinsurance	1,377,179
Insurance | Third party claims-made business | 2011
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	290,124	291,477	289,974	288,038	301,240	322,934	317,074	322,274	330,898	287,607
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	276,887	269,579	254,300	240,267	228,450	208,665	175,139	130,424	72,365	13,740
Total of IBNR liabilities plus expected development on reported claims	$ 4,594
Cumulative number of reported claims | claims	11,762
Insurance | Third party claims-made business | 2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 285,236	284,875	277,388	275,388	291,010	313,622	318,161	319,961	317,360
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	255,098	251,078	227,179	209,097	190,200	164,605	121,112	69,020	17,709
Total of IBNR liabilities plus expected development on reported claims	$ 13,772
Cumulative number of reported claims | claims	14,760
Insurance | Third party claims-made business | 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 271,262	281,751	290,961	294,465	320,284	324,167	320,387	301,715
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	245,504	238,798	217,030	197,907	179,302	137,890	87,408	19,015
Total of IBNR liabilities plus expected development on reported claims	$ 15,306
Cumulative number of reported claims | claims	14,543
Insurance | Third party claims-made business | 2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 291,729	297,485	281,513	278,706	298,715	279,544	264,354
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	243,338	229,512	207,640	172,835	129,502	63,296	13,815
Total of IBNR liabilities plus expected development on reported claims	$ 29,279
Cumulative number of reported claims | claims	13,935
Insurance | Third party claims-made business | 2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 252,329	255,276	259,902	276,328	277,437	258,817
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	193,130	174,108	126,452	100,048	52,019	9,061
Total of IBNR liabilities plus expected development on reported claims	$ 29,255
Cumulative number of reported claims | claims	13,817
Insurance | Third party claims-made business | 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 321,850	314,515	308,195	291,377	275,119
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	205,514	158,159	127,229	68,178	10,547
Total of IBNR liabilities plus expected development on reported claims	$ 61,156
Cumulative number of reported claims | claims	15,734
Insurance | Third party claims-made business | 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 308,401	311,980	285,993	270,523
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	143,149	113,047	67,572	9,289
Total of IBNR liabilities plus expected development on reported claims	$ 82,537
Cumulative number of reported claims | claims	15,923
Insurance | Third party claims-made business | 2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 319,956	314,412	272,844
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	118,184	68,300	12,255
Total of IBNR liabilities plus expected development on reported claims	$ 123,386
Cumulative number of reported claims | claims	14,988
Insurance | Third party claims-made business | 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 317,668	289,463
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	65,345	12,387
Total of IBNR liabilities plus expected development on reported claims	$ 186,452
Cumulative number of reported claims | claims	18,871
Insurance | Third party claims-made business | 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 383,914
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	17,098
Total of IBNR liabilities plus expected development on reported claims	$ 327,587
Cumulative number of reported claims | claims	21,538
Insurance | Multi-line and other specialty
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 4,676,493
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	3,434,155
All outstanding liabilities before 2008, net of reinsurance	31,453
Liabilities for losses and loss adjustment expenses, net of reinsurance	1,273,791
Insurance | Multi-line and other specialty | 2011
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	166,577	170,091	170,350	168,888	172,403	172,649	176,545	182,979	188,766	183,081
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	162,995	162,460	159,526	157,199	151,710	148,049	136,686	117,927	103,372	$ 51,312
Total of IBNR liabilities plus expected development on reported claims	$ 1,790
Cumulative number of reported claims | claims	44,989
Insurance | Multi-line and other specialty | 2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 244,246	244,191	247,279	247,050	255,277	256,106	258,467	264,217	253,525
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	239,244	236,282	232,987	231,776	222,929	209,124	190,064	165,836	$ 78,337
Total of IBNR liabilities plus expected development on reported claims	$ 2,551
Cumulative number of reported claims | claims	55,512
Insurance | Multi-line and other specialty | 2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 270,853	273,177	275,386	271,687	281,697	274,483	283,112	274,361
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	260,374	257,744	251,698	237,898	222,086	185,611	152,773	$ 86,791
Total of IBNR liabilities plus expected development on reported claims	$ 4,661
Cumulative number of reported claims | claims	72,323
Insurance | Multi-line and other specialty | 2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 418,512	410,366	398,240	387,082	370,442	373,978	349,754
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	380,041	367,026	341,580	306,411	255,332	206,444	$ 109,236
Total of IBNR liabilities plus expected development on reported claims	$ 12,232
Cumulative number of reported claims | claims	111,727
Insurance | Multi-line and other specialty | 2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 471,865	456,329	443,258	420,642	418,761	398,755
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	409,455	380,818	350,781	304,197	250,360	$ 142,009
Total of IBNR liabilities plus expected development on reported claims	$ 18,596
Cumulative number of reported claims | claims	151,598
Insurance | Multi-line and other specialty | 2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 537,591	516,239	514,650	504,586	482,653
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	464,774	425,642	382,805	323,681	$ 181,415
Total of IBNR liabilities plus expected development on reported claims	$ 28,282
Cumulative number of reported claims | claims	177,931
Insurance | Multi-line and other specialty | 2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 615,833	578,341	579,217	551,688
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	480,336	419,454	363,275	$ 187,606
Total of IBNR liabilities plus expected development on reported claims	$ 45,947
Cumulative number of reported claims | claims	221,643
Insurance | Multi-line and other specialty | 2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 629,299	621,534	570,069
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	464,970	399,852	$ 214,475
Total of IBNR liabilities plus expected development on reported claims	$ 74,894
Cumulative number of reported claims | claims	247,622
Insurance | Multi-line and other specialty | 2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 667,415	613,638
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	397,104	$ 213,950
Total of IBNR liabilities plus expected development on reported claims	$ 134,996
Cumulative number of reported claims | claims	234,383
Insurance | Multi-line and other specialty | 2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 654,302
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	174,862
Total of IBNR liabilities plus expected development on reported claims	$ 403,044
Cumulative number of reported claims | claims	117,814

X

- Definition

Amount, after reinsurance, of paid claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

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- Definition

Undiscounted amount, after reinsurance, of incurred-but-not-reported (IBNR) liabilities plus expected development on reported claims, for claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

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Undiscounted amount, after reinsurance, of incurred claims and allocated claim adjustment expense used in claims development for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

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- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts. Excludes unallocated claim adjustment expense.

+ References

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- Definition

Undiscounted amount, after reinsurance, of the liability for unpaid claims and allocated claim adjustment expense for short-duration insurance contracts for accident years not separately presented in claim development information. Excludes unallocated claim adjustment expense.

+ References

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- Definition

Cumulative number of reported claims for short-duration insurance contracts.

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

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No definition available.

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