ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Reclassifications out of accumulated other comprehensive income (loss)
Benefits and settlement expenses, net of reinsurance ceded	$ (747,816)	$ (557,866)	$ (1,476,335)	$ (1,139,746)
Realized investment gains (losses): All other investments	80,148	(109,978)	152,262	(114,123)
Net impairment losses recognized in earnings	(1,460)	(4,000)	(3,051)	(8,584)
Income before income tax	162,210	157,013	287,415	274,640
Tax (expense) or benefit	(54,233)	(53,814)	(95,799)	(93,150)
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	(614)	(580)	(1,284)	(1,077)
Income before income tax	(614)	(580)	(1,284)	(1,077)
Tax (expense) or benefit	215	203	449	377
Net income	(399)	(377)	(835)	(700)
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	20,198	21,518	27,568	33,828
Net impairment losses recognized in earnings	(1,460)	(4,000)	(3,051)	(8,584)
Income before income tax	18,738	17,518	24,517	25,244
Tax (expense) or benefit	(6,558)	(6,131)	(8,581)	8,835
Net income	12,180	11,387	15,936	(16,409)
Postretirement Benefits Liability Adjustment | Amount Reclassified from Accumulated Other Comprehensive Income (Loss)
Reclassifications out of accumulated other comprehensive income (loss)
Amortization of net actuarial gain/(loss)	(1,900)		(3,800)
Amortization of prior service credit/(cost)	95		190
Income before income tax	(1,805)		(3,610)
Tax (expense) or benefit	632		1,263
Net income	$ (1,173)		$ (2,347)