OTHER COMPREHENSIVE INCOME (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Before Tax Amount
Other Comprehensive Income (Loss), before Tax	$ 56,594	$ 36,797	$ 270,453	$ 309,267
Tax (Expense) Benefit
Other Comprehensive Income (Loss), Tax	713	(1,381)	(6,999)	(22,297)
Net of Tax Amount
Adjustment for reclassification of net realized investment losses and OTTI losses recognized in net income	(13,286)	(2,642)	10,169	42,620
Other Comprehensive Income (Loss), Net of Tax	57,307	35,416	263,454	286,970
Unrealized gains (losses) on available for sale investments, net of tax [Member]
Before Tax Amount
Unrealized investment gains arising during the period	64,431	40,125	215,360	263,235
Adjustment for reclassification of net realized investment gains and OTTI losses recognized in net income	(15,925)	(5,050)	8,269	40,338
Other Comprehensive Income (Loss), before Tax	48,506	35,075	223,629	303,573
Tax (Expense) Benefit
Unrealized investment gains arising during the period	(1,926)	(3,789)	(8,899)	(24,579)
Adjustment for reclassification of net realized investment gains and OTTI losses recognized in net income	2,639	2,408	1,900	2,282
Other Comprehensive Income (Loss), Tax	713	(1,381)	(6,999)	(22,297)
Net of Tax Amount
Unrealized investment gains arising during the period	62,505	36,336	206,461	238,656
Adjustment for reclassification of net realized investment losses and OTTI losses recognized in net income	(13,286)	(2,642)	10,169	42,620
Other Comprehensive Income (Loss), Net of Tax	49,219	33,694	216,630	281,276
Accumulated Other-than-Temporary Impairment, net of tax [Member]
Before Tax Amount
Other Comprehensive Income (Loss), before Tax	0	0	0	0
Tax (Expense) Benefit
Other Comprehensive Income (Loss), Tax	0	0	0	0
Net of Tax Amount
Other Comprehensive Income (Loss), Net of Tax	0	0	0	0
Cumulative foreign currency translation adjustments, net of tax [Member]
Before Tax Amount
Other Comprehensive Income (Loss), before Tax	8,088	1,722	46,824	5,694
Tax (Expense) Benefit
Other Comprehensive Income (Loss), Tax	0	0	0	0
Net of Tax Amount
Other Comprehensive Income (Loss), Net of Tax	$ 8,088	$ 1,722	$ 46,824	$ 5,694