INVESTMENT OPERATIONS (Details 4) (USD $)				3 Months Ended							3 Months Ended	12 Months Ended									3 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Below investment grade	Mar. 31, 2013 Fixed maturities	Mar. 31, 2012 Fixed maturities	Dec. 31, 2012 Fixed maturities	Mar. 31, 2013 Residential mortgage-backed securities	Dec. 31, 2012 Residential mortgage-backed securities	Mar. 31, 2013 Commercial mortgage-backed securities	Dec. 31, 2012 Commercial mortgage-backed securities	Mar. 31, 2013 Other asset-backed securities	Dec. 31, 2012 Other asset-backed securities	Mar. 31, 2013 U.S. government-related securities	Dec. 31, 2012 U.S. government-related securities	Mar. 31, 2013 Other government-related securities	Dec. 31, 2012 Other government-related securities	Mar. 31, 2013 States, municipals, and political subdivisions	Dec. 31, 2012 States, municipals, and political subdivisions	Mar. 31, 2013 Corporate bonds	Dec. 31, 2012 Corporate bonds	Mar. 31, 2013 Equity securities	Mar. 31, 2012 Equity securities	Dec. 31, 2012 Equity securities
Fair Value
Less Than 12 Months	$ 1,995,683,000	$ 1,574,080,000					$ 127,940,000	$ 100,412,000	$ 112,880,000	$ 50,506,000	$ 74,375,000	$ 479,223,000	$ 206,309,000	$ 106,806,000	$ 20,003,000	$ 14,955,000	$ 11,521,000	$ 11,526,000	$ 1,387,338,000	$ 775,593,000	$ 55,317,000		$ 35,059,000
12 Months or More	1,019,077,000	793,440,000					99,519,000	166,000,000			602,783,000	242,558,000			3,617,000				284,166,000	363,128,000	28,992,000		21,754,000
Total	3,014,760,000	2,367,520,000					227,459,000	266,412,000	112,880,000	50,506,000	677,158,000	721,781,000	206,309,000	106,806,000	23,620,000	14,955,000	11,521,000	11,526,000	1,671,504,000	1,138,721,000	84,309,000		56,813,000
Unrealized Loss
Less Than 12 Months	(82,175,000)	(68,035,000)					(23,734,000)	(9,578,000)	(2,085,000)	(598,000)	(9,968,000)	(28,179,000)	(1,723,000)	(591,000)	(2,000)	(45,000)	(269,000)	(264,000)	(44,151,000)	(23,630,000)	(243,000)		(5,150,000)
12 Months or More	(113,970,000)	(72,622,000)					(13,042,000)	(9,769,000)			(74,371,000)	(33,245,000)			(16,000)				(20,061,000)	(24,765,000)	(6,480,000)		(4,843,000)
Total	(196,145,000)	(140,657,000)					(36,776,000)	(19,347,000)	(2,085,000)	(598,000)	(84,339,000)	(61,424,000)	(1,723,000)	(591,000)	(18,000)	(45,000)	(269,000)	(264,000)	(64,212,000)	(48,395,000)	(6,723,000)		(9,993,000)
Percentage of underlying collateral including student-loan backed auction rate securities guaranteed by the Federal Family Education Loan Program ("FFELP"), minimum											97.00%	97.00%
Available-for-sale securities, fair value	27,482,932,000	27,214,682,000	1,600,000,000	27,079,561,000		26,762,670,000	1,717,910,000	1,839,330,000	916,155,000	869,823,000	946,561,000	975,013,000	1,207,052,000	1,168,446,000	88,477,000	100,778,000	1,433,521,000	1,443,653,000	20,769,885,000	20,365,627,000	353,680,000		354,160,000
Available-for-sale securities, amortized cost	24,624,279,000	24,104,126,000	1,600,000,000	24,228,625,000		23,654,002,000	1,665,681,000	1,766,260,000	853,334,000	797,844,000	1,013,575,000	1,023,649,000	1,142,772,000	1,097,501,000	82,172,000	93,565,000	1,179,314,000	1,188,019,000	18,291,777,000	17,687,164,000	345,963,000		352,272,000
Securities in trading portfolio			367,500,000	3,000,000,000		3,000,000,000															22,400,000		19,600,000
Securities not publicly traded			420,700,000
Change in unrealized gains (losses), net of income tax				$ (167,526,000)	$ 19,462,000																$ 3,789,000	$ 5,106,000