INVESTMENT IN RELATED PARTY INVESTMENT FUND Summarized Income Statements of SILP (Details) - USD ($)	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Realized and change in unrealized gains (losses)
GLRE Limited Partners’ share of net income (loss)	$ (42,126,000)	$ 30,756,000
Solasglas Investment LP (SILP)
Investment income
Dividend income (net of withholding taxes)	747,000	1,240,000
Interest income	209,000	686,000
Total Investment income	956,000	1,926,000
Expenses
Management fee	(662,000)	(2,014,000)
Interest	(17,000)	(1,374,000)
Dividends	(145,000)	(1,070,000)
Professional fees and other	(208,000)	(380,000)
Total expenses	(1,032,000)	(4,838,000)
Net investment income (loss)	(76,000)	(2,912,000)
Realized and change in unrealized gains (losses)
Net realized gain (loss)	(11,953,000)	(7,175,000)
Net change in unrealized appreciation (depreciation)	(39,793,000)	49,753,000
Net gain (loss) on investment transactions	(51,746,000)	42,578,000
Net income (loss)	(51,822,000)	39,666,000
GLRE Limited Partners’ share of net income (loss)	(42,126,000)
Management fee	662,000	2,014,000
Investment Advisory Agreement | Board of Directors Chairman
Realized and change in unrealized gains (losses)
Incentive fee expense	$ 0	$ 3,400,000