FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets:
Available-for-sale securities	$ 32,661,058	$ 27,214,682
Trading securities	2,800,000
Total fixed maturity securities	34,797,757	29,769,978
Equity securities	602,388	373,715
Other long-term investments	210,320	130,428
Short-term investments	133,024	216,787
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Liabilities:
Other liabilities	455,161	657,874
Fixed maturities
Assets:
Available-for-sale securities	31,999,267	26,762,670
Trading securities	2,800,000	3,000,000
Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,445,068	1,839,330
Commercial mortgage-backed securities
Assets:
Available-for-sale securities	970,656	869,823
Other asset-backed securities
Assets:
Available-for-sale securities	871,983	975,013
U.S. government-related securities
Assets:
Available-for-sale securities	1,507,890	1,168,446
States, municipalities, and political subdivisions
Assets:
Available-for-sale securities	1,410,829	1,443,653
Other government-related securities
Assets:
Available-for-sale securities	51,427	100,778
Corporate bonds
Assets:
Available-for-sale securities	25,741,414	20,365,627
Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities	1,402,580	1,214,899
Equity securities	483,482	273,072
Other long-term investments	56,469	23,639
Short-term investments	131,421	214,295
Total investments	2,073,952	1,725,905
Cash	345,579	269,582
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Total assets measured at fair value on a recurring basis	15,994,587	12,159,721
Liabilities:
Other liabilities	30,241	19,187
Total liabilities measured at fair value on a recurring basis	30,241	19,187
Measured at fair value on a recurring basis | Level 1 | Fixed maturities
Assets:
Available-for-sale securities	1,211,248	910,195
Trading securities	191,332	304,704
Measured at fair value on a recurring basis | Level 1 | U.S. government-related securities
Assets:
Available-for-sale securities	1,211,141	909,988
Trading securities	191,332	304,704
Measured at fair value on a recurring basis | Level 1 | Corporate bonds
Assets:
Available-for-sale securities	107	207
Measured at fair value on a recurring basis | Level 2
Assets:
Total fixed maturity securities	31,071,550	27,696,104
Equity securities	50,927	35,116
Other long-term investments	54,965	58,134
Short-term investments	1,603	2,492
Total investments	31,179,045	27,791,846
Assets related to separate accounts
Total assets measured at fair value on a recurring basis	31,179,045	27,791,846
Liabilities:
Other liabilities	191,182	27,250
Total liabilities measured at fair value on a recurring basis	191,182	27,250
Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities	28,688,568	25,064,150
Trading securities	2,382,982	2,631,954
Measured at fair value on a recurring basis | Level 2 | Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,445,040	1,839,326
Trading securities	310,877	357,803
Measured at fair value on a recurring basis | Level 2 | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	970,656	869,823
Trading securities	158,570	171,073
Measured at fair value on a recurring basis | Level 2 | Other asset-backed securities
Assets:
Available-for-sale securities	326,175	378,870
Trading securities	93,278	87,395
Measured at fair value on a recurring basis | Level 2 | U.S. government-related securities
Assets:
Available-for-sale securities	296,749	258,458
Trading securities	4,906	1,169
Measured at fair value on a recurring basis | Level 2 | States, municipalities, and political subdivisions
Assets:
Available-for-sale securities	1,407,154	1,439,378
Trading securities	260,892	278,898
Measured at fair value on a recurring basis | Level 2 | Other government-related securities
Assets:
Available-for-sale securities	51,427	80,767
Trading securities	57,097	63,444
Measured at fair value on a recurring basis | Level 2 | Corporate bonds
Assets:
Available-for-sale securities	24,191,367	20,197,528
Trading securities	1,497,362	1,672,172
Measured at fair value on a recurring basis | Level 3
Assets:
Total fixed maturity securities	2,323,627	858,975
Equity securities	67,979	65,527
Other long-term investments	98,886	48,655
Total investments	2,490,492	973,157
Assets related to separate accounts
Total assets measured at fair value on a recurring basis	2,490,492	973,157
Liabilities:
Annuity account balances	107,000	129,468
Other liabilities	233,738	611,437
Total liabilities measured at fair value on a recurring basis	340,738	740,905
Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities	2,099,451	788,325
Trading securities	224,176	70,650
Measured at fair value on a recurring basis | Level 3 | Residential mortgage-backed securities
Assets:
Available-for-sale securities	28	4
Measured at fair value on a recurring basis | Level 3 | Other asset-backed securities
Assets:
Available-for-sale securities	545,808	596,143
Trading securities	194,977	70,535
Measured at fair value on a recurring basis | Level 3 | States, municipalities, and political subdivisions
Assets:
Available-for-sale securities	3,675	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	1,549,940	167,892
Trading securities	29,199	115
Measured at fair value on a recurring basis | Total
Assets:
Total fixed maturity securities	34,797,757	29,769,978
Equity securities	602,388	373,715
Other long-term investments	210,320	130,428
Short-term investments	133,024	216,787
Total investments	35,743,489	30,490,908
Cash	345,579	269,582
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Total assets measured at fair value on a recurring basis	49,664,124	40,924,724
Liabilities:
Annuity account balances	107,000	129,468
Other liabilities	455,161	657,874
Total liabilities measured at fair value on a recurring basis	562,161	787,342
Measured at fair value on a recurring basis | Total | Fixed maturities
Assets:
Available-for-sale securities	31,999,267	26,762,670
Trading securities	2,798,490	3,007,308
Measured at fair value on a recurring basis | Total | Residential mortgage-backed securities
Assets:
Available-for-sale securities	1,445,068	1,839,330
Trading securities	310,877	357,803
Measured at fair value on a recurring basis | Total | Commercial mortgage-backed securities
Assets:
Available-for-sale securities	970,656	869,823
Trading securities	158,570	171,073
Measured at fair value on a recurring basis | Total | Other asset-backed securities
Assets:
Available-for-sale securities	871,983	975,013
Trading securities	288,255	157,930
Measured at fair value on a recurring basis | Total | U.S. government-related securities
Assets:
Available-for-sale securities	1,507,890	1,168,446
Trading securities	196,238	305,873
Measured at fair value on a recurring basis | Total | States, municipalities, and political subdivisions
Assets:
Available-for-sale securities	1,410,829	1,443,653
Trading securities	260,892	278,898
Measured at fair value on a recurring basis | Total | Other government-related securities
Assets:
Available-for-sale securities	51,427	100,778
Trading securities	57,097	63,444
Measured at fair value on a recurring basis | Total | Corporate bonds
Assets:
Available-for-sale securities	25,741,414	20,365,627
Trading securities	$ 1,526,561	$ 1,672,287