FAIR VALUE OF FINANCIAL INSTRUMENTS (Details 2) (USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013	Dec. 31, 2012
Determination of fair values
Number of primary sources of information used for determining fair value	1
Total number of primary sources of information available for determining fair value	3
Minimum percentage of the Company's fixed maturity securities priced by third party pricing services	90.00%
Number of independent non-binding broker quotes obtained per security	1
Percentage of derivatives excluding embedded derivatives that were priced using exchange prices or independent broker quotations	97.20%
Annuity account balances
Annuity account balances
Discount rate curve, base rate	LIBOR
Equity indexed annuities, discount rate for one month (as a percent)	0.33%
Equity indexed annuities, discount rate for five years (as a percent)	1.91%
Equity indexed annuities, discount rate for thirty years (as a percent)	4.28%
Level 3
Annuity account balances
Financial instruments that are valued using broker quotes	72,000,000	71,100,000
Financial instruments with book value approximating fair value	73,200,000	73,200,000
Level 3 | Annuity account balances
Liabilities:
Annuity account balances	123,681,000	129,468,000
Level 3 | Annuity account balances | Actuarial cash flow model
Unobservable input
Mortality (as a percent)	57.00%	57.00%
Asset earned rate (as a percent)	5.81%	5.81%
Withdrawal rate (as a percent)	2.20%	2.20%
Level 3 | Annuity account balances | Actuarial cash flow model | Minimum
Unobservable input
Lapse (as a percent)	2.20%	2.20%
Nonperformance risk (as a percent)	0.13%	0.09%
Expenses per Policy	88	88
Return on Assets (as a percent)	1.50%	1.50%
Level 3 | Annuity account balances | Actuarial cash flow model | Maximum
Unobservable input
Lapse (as a percent)	45.00%	45.00%
Nonperformance risk (as a percent)	1.29%	1.34%
Expenses per Policy	108	108
Return on Assets (as a percent)	1.85%	1.85%
Asset-Backed Securities | Level 2
Determination of fair values
Carrying amount	3,600,000,000
Asset-Backed Securities | Level 3
Determination of fair values
Carrying amount	632,100,000
Other asset-backed securities
Determination of fair values
Percentage of underlying collateral of student-loan backed auction rate securities guaranteed by the Federal Family Education Loan Program ("FFELP"), minimum	97.00%	97.00%
Other asset-backed securities | Level 3
Determination of fair values
Carrying amount	560,668,000	596,143,000
Annuity account balances
Financial instruments that are valued using broker quotes	71,400,000	70,500,000
Other asset-backed securities | Level 3 | Discounted cash flow | Minimum
Unobservable input
Liquidity premium (as a percent)	1.00%	0.72%
Paydown rate (as a percent)	10.08%	8.51%
Other asset-backed securities | Level 3 | Discounted cash flow | Maximum
Unobservable input
Liquidity premium (as a percent)	1.69%	1.68%
Paydown rate (as a percent)	14.64%	18.10%
Other asset-backed securities | Level 3 | Discounted cash flow | Weighted average
Unobservable input
Liquidity premium (as a percent)	1.14%	1.29%
Paydown rate (as a percent)	12.47%	11.40%
Other asset-backed securities | Level 3 | Trading securities
Determination of fair values
Carrying amount	71,400,000
Percentage of underlying collateral of student-loan backed auction rate securities guaranteed by the Federal Family Education Loan Program ("FFELP"), minimum	97.00%
Corporate bonds, U.S. Government-related securities, and Other government related securities | Level 2
Determination of fair values
Carrying amount	24,400,000,000
Corporate bonds, U.S. Government-related securities, and Other government related securities | Level 3
Determination of fair values
Carrying amount	154,000,000
Equity securities | Level 3
Annuity account balances
Financial instruments that are valued using broker quotes	600,000	600,000
Financial instruments with book value approximating fair value	68,800,000	68,900,000
Equity securities | Level 2 and Level 3
Determination of fair values
Carrying amount	106,500,000
Federal Home Loan Bank Stock	64,600,000
Embedded derivative - GMWB
Liabilities:
Fair value	3,100,000,000
Annuity account balances
Discount rate curve, base rate	LIBOR
Unobservable input
Mortality (as a percent)	57.00%
Embedded derivative - GMWB | Trading securities
Determination of fair values
Carrying amount	2,700,000,000
Embedded derivative - GMWB | Level 3
Liabilities:
Fair value	88,739,000	169,041,000
Embedded derivative - GMWB | Level 3 | Actuarial cash flow model
Unobservable input
Mortality (as a percent)	57.00%	57.00%
Embedded derivative - GMWB | Level 3 | Actuarial cash flow model | Minimum
Unobservable input
Lapse (as a percent)	0.00%	0.00%
Utilization (as a percent)	93.00%	93.00%
Nonperformance risk (as a percent)	0.13%	0.09%
Embedded derivative - GMWB | Level 3 | Actuarial cash flow model | Maximum
Unobservable input
Lapse (as a percent)	24.00%	24.00%
Utilization (as a percent)	100.00%	100.00%
Nonperformance risk (as a percent)	1.29%	1.34%
Corporate bonds | Level 3
Determination of fair values
Carrying amount	129,667,000	168,007,000
Corporate bonds | Level 3 | Discounted cash flow | Minimum
Unobservable input
Spread over treasury (as a percent)	0.97%	0.92%
Corporate bonds | Level 3 | Discounted cash flow | Maximum
Unobservable input
Spread over treasury (as a percent)	7.75%	7.75%
Corporate bonds | Level 3 | Discounted cash flow | Weighted average
Unobservable input
Spread over treasury (as a percent)	2.67%	3.34%
Other government-related securities | Level 3
Determination of fair values
Carrying amount	20,003,000	20,011,000
Other government-related securities | Level 3 | Discounted cash flow | Weighted average
Unobservable input
Spread over treasury (as a percent)	0.30%	0.30%
Fixed maturity securities | Level 3
Annuity account balances
Financial instruments with book value approximating fair value	4,400,000	4,300,000