INVESTMENTS (DETAILS 7) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Net Investment Income [Line Items]
Gross investment income									$ 383,544	$ 337,034	$ 378,377
Investment expenses									(30,209)	(31,698)	(35,611)
Net investment income	$ 95,517	$ 116,923	$ 91,730	$ 49,164	$ 79,000	$ 45,685	$ 88,544	$ 92,107	353,335	305,336	342,766
Fixed Maturities [Member]
Net Investment Income [Line Items]
Gross investment income									305,459	294,725	296,663
Other Investments [Member]
Net Investment Income [Line Items]
Gross investment income									42,514	20,148	57,621
Equity Securities [Member]
Net Investment Income [Line Items]
Gross investment income									16,306	11,289	11,832
Mortgage loans [Member]
Net Investment Income [Line Items]
Gross investment income									7,996	1,861	0
Cash And Cash Equivalents [Member]
Net Investment Income [Line Items]
Gross investment income									9,209	8,572	11,536
Short-term Investments [Member]
Net Investment Income [Line Items]
Gross investment income									$ 2,060	$ 439	$ 725