OTHER COMPREHENSIVE INCOME (LOSS) (Reclassifications Out of AOCI Into Net Income (Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Reclassification out of accumulated comprehensive income into net income available to common shareholders [Line Items]
Other realized gains (losses)	$ (41,668)	$ 16,803
Impairment losses	(1,190)	0
OTTI losses	0	(4,036)
Income (loss) before income taxes and interest in income (loss) of equity method investments	(159,117)	107,796
Income tax (expense) benefit	4,867	(1,234)
Net income (loss) available (attributable) to common shareholders	(185,390)	98,125
Unrealized gains (losses) on available for sale investments | Reclassification out of Accumulated Other Comprehensive Income
Reclassification out of accumulated comprehensive income into net income available to common shareholders [Line Items]
Other realized gains (losses)	(2,936)	(9,838)
Impairment losses	(1,190)	0
OTTI losses	0	(4,036)
Income (loss) before income taxes and interest in income (loss) of equity method investments	(4,126)	(13,874)
Income tax (expense) benefit	(1,522)	504
Net income (loss) available (attributable) to common shareholders	$ (5,648)	$ (13,370)