INVESTMENT OPERATIONS (Details 4) (USD $)	6 Months Ended			3 Months Ended		6 Months Ended							6 Months Ended	12 Months Ended									3 Months Ended		6 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Jun. 30, 2012 Below investment grade	Jun. 30, 2012 Fixed maturities	Jun. 30, 2011 Fixed maturities	Jun. 30, 2012 Fixed maturities	Jun. 30, 2011 Fixed maturities	Dec. 31, 2011 Fixed maturities	Jun. 30, 2012 Residential mortgage-backed securities	Dec. 31, 2011 Residential mortgage-backed securities	Jun. 30, 2012 Commercial mortgage-backed securities	Dec. 31, 2011 Commercial mortgage-backed securities	Jun. 30, 2012 Other asset-backed securities	Dec. 31, 2011 Other asset-backed securities	Jun. 30, 2012 U.S. government-related securities	Dec. 31, 2011 U.S. government-related securities	Jun. 30, 2012 Other government-related securities	Dec. 31, 2011 Other government-related securities	Jun. 30, 2012 States, municipals, and political subdivisions	Dec. 31, 2011 States, municipals, and political subdivisions	Jun. 30, 2012 Corporate bonds	Dec. 31, 2011 Corporate bonds	Jun. 30, 2012 Equity securities	Jun. 30, 2011 Equity securities	Jun. 30, 2012 Equity securities	Jun. 30, 2011 Equity securities	Dec. 31, 2011 Equity securities
Fair Value
Less Than 12 Months	$ 1,817,107,000	$ 2,828,967,000							$ 210,561,000	$ 276,216,000	$ 86,770,000	$ 78,893,000	$ 478,279,000	$ 531,653,000		$ 21,311,000	$ 14,863,000		$ 509,000		$ 1,012,629,000	$ 1,870,256,000	$ 13,496,000		$ 13,496,000		$ 50,638,000
12 Months or More	1,156,140,000	1,260,898,000							360,891,000	524,251,000			207,480,000	190,639,000							559,922,000	523,913,000	27,847,000		27,847,000		22,095,000
Total	2,973,247,000	4,089,865,000							571,452,000	800,467,000	86,770,000	78,893,000	685,759,000	722,292,000		21,311,000	14,863,000		509,000		1,572,551,000	2,394,169,000	41,343,000		41,343,000		72,733,000
Unrealized Loss
Less Than 12 Months	(110,855,000)	(192,058,000)							(13,386,000)	(15,308,000)	(1,315,000)	(4,229,000)	(41,230,000)	(32,074,000)		(58,000)	(137,000)		(9,000)		(46,999,000)	(131,953,000)	(7,779,000)		(7,779,000)		(8,436,000)
12 Months or More	(174,583,000)	(255,294,000)							(43,524,000)	(70,394,000)			(52,333,000)	(58,824,000)							(73,856,000)	(117,917,000)	(4,870,000)		(4,870,000)		(8,159,000)
Total	(285,438,000)	(447,352,000)							(56,910,000)	(85,702,000)	(1,315,000)	(4,229,000)	(93,563,000)	(90,898,000)		(58,000)	(137,000)		(9,000)		(120,855,000)	(249,870,000)	(12,649,000)		(12,649,000)		(16,595,000)
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	26,149,476,000	25,288,601,000	1,700,000,000	25,808,681,000		25,808,681,000		24,997,600,000	2,127,244,000	2,337,044,000	745,831,000	550,527,000	921,744,000	913,029,000	1,317,213,000	1,215,679,000	108,176,000	93,017,000	1,396,086,000	1,327,713,000	19,192,387,000	18,560,591,000	295,849,000		295,849,000		275,372,000
Available-for-sale securities, amortized cost	23,752,892,000	23,451,332,000	1,900,000,000	23,406,617,000		23,406,617,000		23,149,166,000	2,089,252,000	2,340,172,000	710,465,000	530,283,000	1,008,490,000	997,398,000	1,239,475,000	1,150,525,000	101,521,000	88,058,000	1,158,642,000	1,154,307,000	17,098,772,000	16,888,423,000	301,329,000		301,329,000		286,537,000
Securities in trading portfolio			334,100,000	3,000,000,000		3,000,000,000		3,000,000,000															18,200,000		18,200,000		17,000,000
Securities not publicly traded			413,400,000
Initial collateral as a percentage of market value of securities loaned	102.00%
Other-than-temporary impairment recognized on certain collateral assets	1,300,000
Change in unrealized gains (losses), net of income tax				$ 340,397,000	$ 169,167,000	$ 359,860,000	$ 197,399,000																$ (1,411,000)	$ (3,377,000)	$ 3,695,000	$ (3,793,000)