INVESTMENTS - Schedule of Net Realized and Unrealized Gains (Losses) on Investments (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on investments	$ (228,087)	$ (641,500)	$ (171,417)	$ (1,968,624)
Fixed maturity investments trading
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on fixed maturity investments trading	(121,112)	(213,493)	(300,089)	(621,799)
Net unrealized gains (losses) on fixed maturity investments trading	(158,226)	(210,665)	14,007	(824,662)
Net realized and unrealized gains (losses) on fixed maturity investments trading	(279,338)	(424,158)	(286,082)	(1,446,461)
Derivatives
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on investment-related derivatives	30,594	(55,580)	(22,295)	(161,946)
Equity investments
Gain (Loss) on Securities [Line Items]
Net realized gains (losses) on equity investments	(10)	3,066	(27,503)	38,638
Net unrealized gains (losses) on equity investments	2,261	(46,301)	62,039	(222,074)
Net realized and unrealized gains (losses) on equity investments	2,251	(43,235)	34,536	(183,436)
Catastrophe bonds
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on other investments	32,474	(126,992)	94,786	(159,913)
Other
Gain (Loss) on Securities [Line Items]
Net realized and unrealized gains (losses) on other investments	$ (14,068)	$ 8,465	$ 7,638	$ (16,868)