INVESTMENT IN RELATED PARTY INVESTMENT FUND - Summarized Statements of Assets, Liabilities and Net Assets of SILP (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Expenses
Total expenses	$ (152,048)	$ (153,416)	$ (482,273)	$ (442,262)
Net investment income (loss)	8,244	6,958	24,611	24,705
Realized and change in unrealized gains (losses)
Net change in unrealized appreciation (depreciation)			1,500
Net gain (loss) on investment transactions	0	(2,555)	(324)	(2,299)
Net increase (decrease) in Partners' capital	35,237	13,477	70,234	69,224
GLRE’s share of the increase (decrease) in Partners' capital	19,844	(1,853)	42,422	27,791
Management fees	1,613	1,238	4,344	3,469
Performance allocation		(206)
Performance allocation	2,205		4,714	3,088
Total	3,818	1,032	9,058	6,557
Solasglas Investments, LP (SILP)
Realized and change in unrealized gains (losses)
GLRE’s share of the increase (decrease) in Partners' capital	19,844	(1,853)	42,422	27,791
Solasglas Investments, LP (SILP)
Investment income
Dividend income (net of withholding taxes)	752	273	2,524	1,624
Interest income	3,540	2,523	10,040	6,415
Total Investment income	4,292	2,796	12,564	8,039
Expenses
Management fee	(1,613)	(1,238)	(4,344)	(3,469)
Interest	(817)	(2,380)	(2,887)	(5,387)
Dividends	(782)	(659)	(2,217)	(1,871)
Professional fees and other	(262)	(507)	(921)	(1,396)
Total expenses	(3,474)	(4,784)	(10,369)	(12,123)
Net investment income (loss)	818	(1,988)	2,195	(4,084)
Realized and change in unrealized gains (losses)
Net realized gain (loss)	23,647	460	86,677	(2,145)
Net change in unrealized appreciation (depreciation)	4,801	(1,191)	(24,582)	52,601
Net gain (loss) on investment transactions	28,448	(731)	62,095	50,456
Net increase (decrease) in Partners' capital	$ 29,265	$ (2,719)	$ 64,289	$ 46,372