ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)
Benefits and settlement expenses, net of reinsurance ceded									$ (2,473,988)	$ (2,317,121)	$ (2,222,220)
Realized investment gains (losses): All other investments									(121,537)	232,836	247,753
Net impairment losses recognized in earnings									(22,447)	(58,144)	(47,321)
Income before income tax	120,403	113,355	78,927	109,814	94,757	106,689	117,065	141,068	422,499	459,579	475,275
Tax (expense) or benefit	(31,931)	(37,107)	(25,923)	(35,936)	(34,615)	(35,778)	(35,438)	(45,212)	(130,897)	(151,043)	(151,519)
Gains and losses on derivative instruments | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)
Benefits and settlement expenses, net of reinsurance ceded									(2,349)
Income before income tax									(2,349)
Tax (expense) or benefit									822
Net of tax									(1,527)
Unrealized gains and losses on available-for-sale securities | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications Out of Accumulated Other Comprehensive Income (Loss)
Realized investment gains (losses): All other investments									66,437
Net impairment losses recognized in earnings									(22,447)
Income before income tax									43,990
Tax (expense) or benefit									(15,396)
Net of tax									$ 28,594