FAIR VALUE OF FINANCIAL INSTRUMENTS (Details) (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Assets:
Available-for-sale securities	$ 32,723,992	$ 27,271,759
Total fixed maturity securities	34,815,931	29,787,959
Equity securities	646,027	411,786
Other long-term investments	307,567	113,364
Short-term investments	134,146	217,812
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Liabilities:
Other liabilities	457,802	657,874
Fixed maturities
Assets:
Available-for-sale securities	32,017,441	26,780,651
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
State, municipalities, and political subdivisions
Assets:
Available-for-sale securities	1,410,829	1,443,713
Other government-related securities
Assets:
Available-for-sale securities	51,427	100,778
Corporate bonds
Assets:
Available-for-sale securities	25,759,588	20,382,051
Level 3 | Other asset-backed securities
Assets:
Total investments	545,808	596,143
Level 3 | Other government-related securities
Assets:
Total investments		20,011
Level 3 | Corporate bonds
Assets:
Total investments	1,555,898	168,007
Measured at fair value on a recurring basis | Level 1
Assets:
Total fixed maturity securities	1,402,580	1,214,899
Equity securities	523,219	307,252
Other long-term investments	56,469	23,639
Short-term investments	132,543	215,320
Total investments	2,114,811	1,761,110
Cash	466,542	368,801
Other assets	10,979	8,239
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Total assets	16,167,388	12,302,384
Liabilities:
Other liabilities	30,241	19,187
Total liabilities	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	31,089,724	27,714,025
Equity securities	50,927	35,116
Other long-term investments	54,965	58,134
Short-term investments	1,603	2,492
Total investments	31,197,219	27,809,767
Assets related to separate accounts
Total assets	31,197,219	27,809,767
Liabilities:
Other liabilities	156,931	27,250
Total liabilities	156,931	27,250
Measured at fair value on a recurring basis | Level 2 | Fixed maturities
Assets:
Available-for-sale securities	28,706,742	25,082,071
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	259,955
Trading securities	4,906	1,169
Measured at fair value on a recurring basis | Level 2 | State, 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	24,209,541	20,213,952
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	859,035
Equity securities	71,881	69,418
Other long-term investments	196,133	31,591
Total investments	2,591,641	960,044
Assets related to separate accounts
Total assets	2,591,641	960,044
Liabilities:
Annuity account balances	107,000	129,468
Other liabilities	270,630	611,437
Total liabilities	377,630	740,905
Measured at fair value on a recurring basis | Level 3 | Fixed maturities
Assets:
Available-for-sale securities	2,099,451	788,385
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 | State, municipalities, and political subdivisions
Assets:
Available-for-sale securities	3,675	4,335
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 | Fair Values
Assets:
Total fixed maturity securities	34,815,931	29,787,959
Equity securities	646,027	411,786
Other long-term investments	307,567	113,364
Short-term investments	134,146	217,812
Total investments	35,903,671	30,530,921
Cash	466,542	368,801
Other assets	10,979	8,239
Assets related to separate accounts
Variable annuity	12,791,438	9,601,417
Variable universal life	783,618	562,817
Total assets	49,956,248	41,072,195
Liabilities:
Annuity account balances	107,000	129,468
Other liabilities	457,802	657,874
Total liabilities	564,802	787,342
Measured at fair value on a recurring basis | Fair Values | Fixed maturities
Assets:
Available-for-sale securities	32,017,441	26,780,651
Trading securities	2,798,490	3,007,308
Measured at fair value on a recurring basis | Fair Values | 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 | Fair Values | 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 | Fair Values | 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 | Fair Values | U.S. government-related securities
Assets:
Available-for-sale securities	1,507,890	1,169,943
Trading securities	196,238	305,873
Measured at fair value on a recurring basis | Fair Values | State, municipalities, and political subdivisions
Assets:
Available-for-sale securities	1,410,829	1,443,713
Trading securities	260,892	278,898
Measured at fair value on a recurring basis | Fair Values | 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 | Fair Values | Corporate bonds
Assets:
Available-for-sale securities	25,759,588	20,382,051
Trading securities	$ 1,526,561	$ 1,672,287