FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2012	Dec. 31, 2011
Assets:
Available-for-sale securities	$ 27,214,682	$ 25,288,601
Trading securities	3,100,000
Total fixed maturity securities	29,769,978	27,957,565	[1]
Equity securities	373,715	292,413	[1]
Other long-term investments	130,428	54,645
Short-term investments	216,787	101,470	[1]
Assets related to separate accounts
Variable annuity	9,601,417	6,741,959	[1]
Variable universal life	562,817	502,617	[1]
Liabilities:
Other liabilities	657,874	455,710
Fixed maturities
Assets:
Available-for-sale securities	26,762,670	24,997,600
Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,839,330	2,337,044
Commercial mortgage-backed securities
Assets:
Available-for-sale securities	869,823	550,527
Other asset-backed securities
Assets:
Available-for-sale securities	975,013	913,029
U.S. government-related securities
Assets:
Available-for-sale securities	1,168,446	1,215,679
States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,443,653	1,327,713
Other government-related securities
Assets:
Available-for-sale securities	100,778	93,017
Corporate bonds
Assets:
Available-for-sale securities	20,365,627	18,560,591
Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities	1,214,899	1,220,311
Equity securities	273,072	211,023
Other long-term investments	23,639	27,757
Short-term investments	214,295	101,470
Total investments	1,725,905	1,560,561
Cash	269,582	169,775
Assets related to separate accounts
Variable annuity	9,601,417	6,741,959
Variable universal life	562,817	502,617
Total assets	12,159,721	8,974,912
Liabilities:
Other liabilities	19,187	2,727
Total liabilities	19,187	2,727
Measured at fair value on a recurring basis | Level 1 | Fixed maturities
Assets:
Available-for-sale securities	910,195	664,710
Trading securities	304,704	555,601
Measured at fair value on a recurring basis | Level 1 | U.S. government-related securities
Assets:
Available-for-sale securities	909,988	664,506
Trading securities	304,704	555,601
Measured at fair value on a recurring basis | Level 1 | Corporate bonds
Assets:
Available-for-sale securities	207	204
Measured at fair value on a recurring basis | Level 2
Assets:
Total fixed maturity securities	27,696,104	25,959,526
Equity securities	35,116	11,310
Other long-term investments	58,134	7,785
Short-term investments	2,492
Total investments	27,791,846	25,978,621
Assets related to separate accounts
Total assets	27,791,846	25,978,621
Liabilities:
Other liabilities	27,250	15,370
Total liabilities	27,250	15,370
Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities	25,064,150	23,583,505
Trading securities	2,631,954	2,376,021
Measured at fair value on a recurring basis | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,839,326	2,337,037
Trading securities	357,803	313,963
Measured at fair value on a recurring basis | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	869,823	550,527
Trading securities	171,073	190,247
Measured at fair value on a recurring basis | Level 2 | Other asset-backed securities
Assets:
Available-for-sale securities	378,870	298,216
Trading securities	87,395	29,585
Measured at fair value on a recurring basis | Level 2 | U.S. government-related securities
Assets:
Available-for-sale securities	258,458	536,173
Trading securities	1,169	255
Measured at fair value on a recurring basis | Level 2 | States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,439,378	1,327,713
Trading securities	278,898	229,032
Measured at fair value on a recurring basis | Level 2 | Other government-related securities
Assets:
Available-for-sale securities	80,767	93,017
Trading securities	63,444	44,845
Measured at fair value on a recurring basis | Level 2 | Corporate bonds
Assets:
Available-for-sale securities	20,197,528	18,440,822
Trading securities	1,672,172	1,568,094
Measured at fair value on a recurring basis | Level 3
Assets:
Total fixed maturity securities	858,975	777,728
Equity securities	65,527	70,080
Other long-term investments	48,655	19,103
Total investments	973,157	866,911
Assets related to separate accounts
Total assets	973,157	866,911
Liabilities:
Annuity account balances	129,468	136,462
Other liabilities	611,437	437,613
Total liabilities	740,905	574,075
Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities	788,325	749,385
Trading securities	70,650	28,343
Measured at fair value on a recurring basis | Level 3 | Residential mortgage-backed securities
Assets:
Available-for-sale securities	4	7
Measured at fair value on a recurring basis | Level 3 | Other asset-backed securities
Assets:
Available-for-sale securities	596,143	614,813
Trading securities	70,535	28,343
Measured at fair value on a recurring basis | Level 3 | U.S. government-related securities
Assets:
Available-for-sale securities		15,000
Measured at fair value on a recurring basis | Level 3 | States, municipals, and political subdivisions
Assets:
Available-for-sale securities	4,275
Measured at fair value on a recurring basis | Level 3 | Other government-related securities
Assets:
Available-for-sale securities	20,011
Measured at fair value on a recurring basis | Level 3 | Corporate bonds
Assets:
Available-for-sale securities	167,892	119,565
Trading securities	115
Measured at fair value on a recurring basis | Total
Assets:
Total fixed maturity securities	29,769,978	27,957,565
Equity securities	373,715	292,413
Other long-term investments	130,428	54,645
Short-term investments	216,787	101,470
Total investments	30,490,908	28,406,093
Cash	269,582	169,775
Assets related to separate accounts
Variable annuity	9,601,417	6,741,959
Variable universal life	562,817	502,617
Total assets	40,924,724	35,820,444
Liabilities:
Annuity account balances	129,468	136,462
Other liabilities	657,874	455,710
Total liabilities	787,342	592,172
Measured at fair value on a recurring basis | Total | Fixed maturities
Assets:
Available-for-sale securities	26,762,670	24,997,600
Trading securities	3,007,308	2,959,965
Measured at fair value on a recurring basis | Total | Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,839,330	2,337,044
Trading securities	357,803	313,963
Measured at fair value on a recurring basis | Total | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	869,823	550,527
Trading securities	171,073	190,247
Measured at fair value on a recurring basis | Total | Other asset-backed securities
Assets:
Available-for-sale securities	975,013	913,029
Trading securities	157,930	57,928
Measured at fair value on a recurring basis | Total | U.S. government-related securities
Assets:
Available-for-sale securities	1,168,446	1,215,679
Trading securities	305,873	555,856
Measured at fair value on a recurring basis | Total | States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,443,653	1,327,713
Trading securities	278,898	229,032
Measured at fair value on a recurring basis | Total | Other government-related securities
Assets:
Available-for-sale securities	100,778	93,017
Trading securities	63,444	44,845
Measured at fair value on a recurring basis | Total | Corporate bonds
Assets:
Available-for-sale securities	20,365,627	18,560,591
Trading securities	$ 1,672,287	$ 1,568,094

[1] Recast from previously reported information