RECLASSIFICATION FROM ACCUMULATED OTHER COMPREHENSIVE INCOME INTO NET INCOME - Summary of Amounts Reclassified out of Accumulated Other Comprehensive Income into Net Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Other-than-temporary impairment (OTTI) on securities	$ 1,509	$ 1,765	$ 8,736	$ 7,838
Total reclassifications	(5,833)	2,444	(20,856)	(7,234)
Accumulated Net Investment Gain (Loss) Including Portion Attributable to Noncontrolling Interest | Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Gain (loss) on settlement of investments, net	(7,342)	679	(29,592)	(15,072)
Other-than-temporary impairment (OTTI) on securities	$ 1,509	$ 1,765	$ 8,736	$ 7,838