SEGMENT INFORMATION (Details) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2024 USD ($)	Sep. 30, 2023 USD ($)	Sep. 30, 2024 USD ($) segment	Sep. 30, 2023 USD ($)
Segment Reporting [Abstract]
Number of reportable segments \| segment			2
Segment Information [Line Items]
Net premiums earned	$ 1,366,701	$ 1,322,564	$ 3,929,221	$ 3,818,508
Other insurance related income (loss)	6,838	10,344	23,704	16,444
Net losses and loss expenses	(831,872)	(783,940)	(2,326,532)	(2,240,840)
Acquisition costs	(274,935)	(263,389)	(794,280)	(747,027)
Underwriting-related general and administrative expenses and corporate expenses	(165,203)	(179,283)	(477,016)	(514,596)
Net investment income	205,100	154,201	563,458	424,802
Foreign exchange (losses) gains	(92,204)	50,570	(61,268)	11,755
Interest expense and financing costs	(16,849)	(16,445)	(51,005)	(50,077)
Reorganization expenses	0	(28,997)	(26,312)	(28,997)
Amortization of intangible assets	(2,729)	(2,729)	(8,188)	(8,188)
Income before income taxes and interest in income of equity method investments	227,029	209,782	741,279	584,113
Income tax (expense) benefit	(47,922)	(24,624)	36,185	(68,078)
Interest in income of equity method investments	1,621	2,940	10,689	2,835
Net income	180,728	188,098	788,153	518,870
Preferred share dividends	7,563	7,563	22,688	22,688
Net income available to common shareholders	173,165	180,535	765,465	496,182
Operating Segments
Segment Information [Line Items]
Gross premiums written	1,935,902	1,905,878	7,030,564	6,572,232
Net premiums written	1,235,985	975,357	4,531,802	4,030,070
Net premiums earned	1,366,701	1,322,564	3,929,221	3,818,508
Other insurance related income (loss)	6,838	10,344	23,704	16,444
Net losses and loss expenses	(831,872)	(783,940)	(2,326,532)	(2,240,840)
Acquisition costs	(274,935)	(263,389)	(794,280)	(747,027)
Underwriting-related general and administrative expenses and corporate expenses	(131,582)	(138,601)	(390,143)	(412,251)
Underwriting income	$ 135,150	$ 146,978	$ 441,970	$ 434,834
Net losses and loss expenses ratio (as a percent)	60.90%	59.30%	59.20%	58.70%
Acquisition cost ratio (as a percent)	20.10%	19.90%	20.20%	19.60%
General and administrative expense ratio (as a percent)	12.10%	13.50%	12.20%	13.40%
Combined ratio (as a percent)	93.10%	92.70%	91.60%	91.70%
Goodwill and intangible assets	$ 279,497	$ 290,413	$ 279,497	$ 290,413
Operating Segments \| Insurance
Segment Information [Line Items]
Gross premiums written	1,526,676	1,457,624	4,915,247	4,557,386
Net premiums written	975,911	885,252	3,192,462	2,788,849
Net premiums earned	1,023,851	885,714	2,900,011	2,544,920
Other insurance related income (loss)	93	(22)	53	90
Net losses and loss expenses	(602,654)	(491,368)	(1,642,110)	(1,398,486)
Acquisition costs	(203,255)	(169,384)	(567,310)	(473,413)
Underwriting-related general and administrative expenses and corporate expenses	(119,249)	(120,330)	(353,230)	(350,494)
Underwriting income	$ 98,786	$ 104,610	$ 337,414	$ 322,617
Net losses and loss expenses ratio (as a percent)	58.90%	55.50%	56.60%	55.00%
Acquisition cost ratio (as a percent)	19.90%	19.10%	19.60%	18.60%
General and administrative expense ratio (as a percent)	11.60%	13.60%	12.20%	13.70%
Combined ratio (as a percent)	90.40%	88.20%	88.40%	87.30%
Goodwill and intangible assets	$ 279,497	$ 290,413	$ 279,497	$ 290,413
Operating Segments \| Reinsurance
Segment Information [Line Items]
Gross premiums written	409,226	448,254	2,115,317	2,014,846
Net premiums written	260,074	90,105	1,339,340	1,241,221
Net premiums earned	342,850	436,850	1,029,210	1,273,588
Other insurance related income (loss)	6,745	10,366	23,651	16,354
Net losses and loss expenses	(229,218)	(292,572)	(684,422)	(842,354)
Acquisition costs	(71,680)	(94,005)	(226,970)	(273,614)
Underwriting-related general and administrative expenses and corporate expenses	(12,333)	(18,271)	(36,913)	(61,757)
Underwriting income	$ 36,364	$ 42,368	$ 104,556	$ 112,217
Net losses and loss expenses ratio (as a percent)	66.90%	67.00%	66.50%	66.10%
Acquisition cost ratio (as a percent)	20.90%	21.50%	22.10%	21.50%
General and administrative expense ratio (as a percent)	3.60%	4.20%	3.50%	4.90%
Combined ratio (as a percent)	91.40%	92.70%	92.10%	92.50%
Goodwill and intangible assets	$ 0	$ 0	$ 0	$ 0
Segment Reconciling Items
Segment Information [Line Items]
Net investment income	205,100	154,201	563,458	424,802
Net investment gains (losses)	32,182	(53,114)	(30,503)	(97,671)
Foreign exchange (losses) gains	(92,204)	50,570	(61,268)	11,755
Interest expense and financing costs	(16,849)	(16,445)	(51,005)	(50,077)
Reorganization expenses	0	(28,997)	(26,312)	(28,997)
Amortization of intangible assets	(2,729)	(2,729)	(8,188)	(8,188)
Corporate expenses
Segment Information [Line Items]
Underwriting-related general and administrative expenses and corporate expenses	$ (33,621)	$ (40,682)	$ (86,873)	$ (102,345)

This item represents the difference between the gross realized gains and losses realized on the sale of debt or equity securities categorized neither as held-to-maturity nor trading securities. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities, the change in fair value of investment-related derivatives not designated as hedges and any hedge ineffectiveness recognized in earnings in relation to investment portfolio-related fair value hedges.

No definition available.