ACCUMULATED OTHER COMPREHENSIVE INCOME (LOSS) (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance			$ 1,811,124
Other comprehensive income (loss) before reclassifications			(1,191,281)
Other comprehensive income relating to other-than-temporary impaired investments for which a portion has been recognized in earnings	(2,865)	23,789	2,570	29,240
Amounts reclassified from accumulated other comprehensive income (loss)			(16,633)
Net current-period other comprehensive income (loss)			(1,205,344)
Ending Balance	605,780		605,780
Unrealized Gains and Losses on Investments
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance			1,814,620
Other comprehensive income (loss) before reclassifications			(1,191,178)
Other comprehensive income relating to other-than-temporary impaired investments for which a portion has been recognized in earnings			2,570
Amounts reclassified from accumulated other comprehensive income (loss)			(17,705)
Net current-period other comprehensive income (loss)			(1,206,313)
Ending Balance	608,307		608,307
Accumulated Gain and Loss Derivatives
Changes in Accumulated Other Comprehensive Income (Loss) by Component
Beginning Balance			(3,496)
Other comprehensive income (loss) before reclassifications			(103)
Amounts reclassified from accumulated other comprehensive income (loss)			1,072
Net current-period other comprehensive income (loss)			969
Ending Balance	$ (2,527)		$ (2,527)