FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Sep. 30, 2012	Dec. 31, 2011
Assets:
Available-for-sale securities	$ 26,863,312	$ 25,288,601
Trading securities	3,100,000
Total fixed maturity securities	29,588,085	27,957,565	[1]
Equity securities	336,276	292,413	[1]
Other long-term investments	134,021	54,645
Short-term investments	110,108	101,470	[1]
Assets related to separate accounts
Variable annuity	8,895,947	6,741,959	[1]
Variable universal life	557,529	502,617	[1]
Liabilities:
Other liabilities	640,426	455,710
Fixed maturities
Assets:
Available-for-sale securities	26,492,248	24,997,600
Residential mortgage-backed securities
Assets:
Available-for-sale securities	2,007,017	2,337,044
Commercial mortgage-backed securities
Assets:
Available-for-sale securities	838,657	550,527
Other asset-backed securities
Assets:
Available-for-sale securities	936,063	913,029
U.S. government-related securities
Assets:
Available-for-sale securities	1,349,193	1,215,679
States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,420,997	1,327,713
Other government-related securities
Assets:
Available-for-sale securities	101,116	93,017
Corporate bonds
Assets:
Available-for-sale securities	19,839,205	18,560,591
Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities	1,203,164	1,220,311
Equity securities	248,145	211,023
Other long-term investments	21,645	27,757
Short-term investments	110,108	101,470
Total investments	1,583,062	1,560,561
Cash	79,566	169,775
Assets related to separate accounts
Variable annuity	8,895,947	6,741,959
Variable universal life	557,529	502,617
Total assets	11,116,104	8,974,912
Liabilities:
Other liabilities	4,447	2,727
Total liabilities	4,447	2,727
Measured at fair value on a recurring basis | Level 1 | Fixed maturities
Assets:
Available-for-sale securities	894,236	664,710
Trading securities	308,928	555,601
Measured at fair value on a recurring basis | Level 1 | U.S. government-related securities
Assets:
Available-for-sale securities	894,031	664,506
Trading securities	308,928	555,601
Measured at fair value on a recurring basis | Level 1 | Corporate bonds
Assets:
Available-for-sale securities	205	204
Measured at fair value on a recurring basis | Level 2
Assets:
Total fixed maturity securities	27,548,319	25,959,526
Equity securities	22,770	11,310
Other long-term investments	66,817	7,785
Total investments	27,637,906	25,978,621
Assets related to separate accounts
Total assets	27,637,906	25,978,621
Liabilities:
Other liabilities	17,630	15,370
Total liabilities	17,630	15,370
Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities	24,835,587	23,583,505
Trading securities	2,712,732	2,376,021
Measured at fair value on a recurring basis | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities	2,007,013	2,337,037
Trading securities	386,861	313,963
Measured at fair value on a recurring basis | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	838,657	550,527
Trading securities	184,932	190,247
Measured at fair value on a recurring basis | Level 2 | Other asset-backed securities
Assets:
Available-for-sale securities	346,425	298,216
Trading securities	81,627	29,585
Measured at fair value on a recurring basis | Level 2 | U.S. government-related securities
Assets:
Available-for-sale securities	455,162	536,173
Trading securities	247	255
Measured at fair value on a recurring basis | Level 2 | States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,416,722	1,327,713
Trading securities	276,449	229,032
Measured at fair value on a recurring basis | Level 2 | Other government-related securities
Assets:
Available-for-sale securities	81,111	93,017
Trading securities	59,077	44,845
Measured at fair value on a recurring basis | Level 2 | Corporate bonds
Assets:
Available-for-sale securities	19,690,497	18,440,822
Trading securities	1,723,539	1,568,094
Measured at fair value on a recurring basis | Level 3
Assets:
Total fixed maturity securities	836,602	777,728
Equity securities	65,361	70,080
Other long-term investments	45,559	19,103
Total investments	947,522	866,911
Assets related to separate accounts
Total assets	947,522	866,911
Liabilities:
Annuity account balances	134,569	136,462
Other liabilities	618,349	437,613
Total liabilities	752,918	574,075
Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities	762,425	749,385
Trading securities	74,177	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	589,638	614,813
Trading securities	74,062	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	20,005
Measured at fair value on a recurring basis | Level 3 | Corporate bonds
Assets:
Available-for-sale securities	148,503	119,565
Trading securities	115
Measured at fair value on a recurring basis | Total
Assets:
Total fixed maturity securities	29,588,085	27,957,565
Equity securities	336,276	292,413
Other long-term investments	134,021	54,645
Short-term investments	110,108	101,470
Total investments	30,168,490	28,406,093
Cash	79,566	169,775
Assets related to separate accounts
Variable annuity	8,895,947	6,741,959
Variable universal life	557,529	502,617
Total assets	39,701,532	35,820,444
Liabilities:
Annuity account balances	134,569	136,462
Other liabilities	640,426	455,710
Total liabilities	774,995	592,172
Measured at fair value on a recurring basis | Total | Fixed maturities
Assets:
Available-for-sale securities	26,492,248	24,997,600
Trading securities	3,095,837	2,959,965
Measured at fair value on a recurring basis | Total | Residential mortgage-backed securities
Assets:
Available-for-sale securities	2,007,017	2,337,044
Trading securities	386,861	313,963
Measured at fair value on a recurring basis | Total | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	838,657	550,527
Trading securities	184,932	190,247
Measured at fair value on a recurring basis | Total | Other asset-backed securities
Assets:
Available-for-sale securities	936,063	913,029
Trading securities	155,689	57,928
Measured at fair value on a recurring basis | Total | U.S. government-related securities
Assets:
Available-for-sale securities	1,349,193	1,215,679
Trading securities	309,175	555,856
Measured at fair value on a recurring basis | Total | States, municipals, and political subdivisions
Assets:
Available-for-sale securities	1,420,997	1,327,713
Trading securities	276,449	229,032
Measured at fair value on a recurring basis | Total | Other government-related securities
Assets:
Available-for-sale securities	101,116	93,017
Trading securities	59,077	44,845
Measured at fair value on a recurring basis | Total | Corporate bonds
Assets:
Available-for-sale securities	19,839,205	18,560,591
Trading securities	$ 1,723,654	$ 1,568,094

[1] Recast from previously reported information