RESERVE FOR CLAIMS AND CLAIM EXPENSES - Schedule of Prior Year Development of the Reserve for Net Claims and Claim Expenses (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	$ (97,081)	$ (104,752)
Property
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(94,667)	(81,693)
Property \| Large catastrophe events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(70,163)	(76,607)
Property \| 2023 Large Loss Events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	1,569
Property \| 2022 Weather-Related Large Losses
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(8,574)	(7,785)
Property \| 2021 Weather-Related Large Lossses
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(36,228)	(32,333)
Property \| 2020 Weather-Related Large Loss Events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(6,128)	6,535
Property \| 2019 Large Loss Events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(4,053)	(15,369)
Property \| 2018 Large Loss Events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(9,461)	(16,259)
Property \| 2017 Large Loss Events
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(7,288)	(11,486)
Property \| Other
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses		90
Property \| Small catastrophe events and attritional loss movements
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(24,504)	(5,086)
Property \| Other small catastrophe events and attritional loss movements
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(24,504)	(5,086)
Property \| Operating Segments
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(94,667)	(81,693)
Casualty and Specialty
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(2,414)	(23,059)
Casualty and Specialty \| Actuarial methods - actual reported claims less than expected claims
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	(2,414)	(23,059)
Casualty and Specialty \| Operating Segments
Liability for Catastrophe Claims [Line Items]
Net (favorable) adverse development of prior accident years net claims and claim expenses	$ (2,414)	$ (23,059)