SUMMARY OF INVESTMENTS (Net Realized Investment Gains and Losses) (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	$ 53,779	$ (20,179)	$ 4,055
AVAILABLE-FOR-SALE
Proceeds from sale of available-for-sale investments	41,760	132,250
Proceeds from sales			7,404
Gross realized gains	302	140	1,046
Gross realized losses	(13)	(517)	(20)
Discontinued Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	0	(1,057)	4,008
AVAILABLE-FOR-SALE
Proceeds from sale of available-for-sale investments	0
Proceeds from sales		0	7,315
Gross realized gains	0	0	1,264
Gross realized losses	0	0	(78)
Continuing and Discontinuing Operations
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	53,779	(21,236)	8,063
Fixed maturities \| Available-for-sale
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	655	(254)	829
Fixed maturities \| Change in fair value
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	1,351	(296)	924
Fixed maturities \| Sales
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	1,993	1,226	244
Equity securities \| Change in fair value
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	51,231	(21,994)	332
Equity securities \| Sales
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	725	1,702	1,610
Mortgage loans
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	(26)	(46)	0
Real Estate
Gain (Loss) on Securities [Line Items]
Net realized investment gains (losses) from continuing operations	$ (2,150)	$ (517)	$ 116

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Amount of realized gain on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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