MORTGAGE LOANS (Details) (USD $)	3 Months Ended		12 Months Ended
	Mar. 31, 2014 item	Mar. 31, 2013	Dec. 31, 2013
Mortgage loans
Mortgage loan holdings	$ 5,390,844,000		$ 5,486,417,000
Amount that would become due for the remainder of 2014, if loans are called at their next call dates	54,900,000
Amount that would become due in 2015 through 2019, if loans are called at their next call dates	1,200,000,000
Amount that would become due in 2020 through 2024, if loans are called at their next call dates	506,400,000
Amount that would become due after 2024, if loans are called at their next call dates	133,300,000
Change in the allowance for credit losses
Ending balance	4,500,000		3,100,000
Commercial mortgage loans
Mortgage loans
Mortgage loan holdings	5,400,000,000
Mortgage loans having participation feature	630,300,000		666,600,000
Income recognized on participating mortgage loans	3,000,000	3,400,000
Nonperforming mortgage loans, foreclosed properties and restructured loans pursuant to pooling and servicing agreement	14,200,000
Nonperforming mortgage loans, foreclosed properties and restructured loans to invested assets (as a percent)	0.03%
Principal balance of loan	0
Mortgage loans accounted for as troubled debt restructurings	5,800,000
Number of loan categories	2
Nonperforming or restructured loans not subject to a pooling and servicing agreement	12,000,000
Loans subject to a pooling and servicing agreement which are nonperforming	2,200,000
Number of nonperforming loans subject to a pooling and servicing agreement which have been restructured	0
Change in the allowance for credit losses
Beginning balance	3,130,000	2,875,000	2,875,000
Charge offs			(6,838,000)
Recoveries	(167,000)		(1,016,000)
Provision	1,542,000		8,109,000
Ending balance	$ 4,505,000		$ 3,130,000
Commercial mortgage loans | Minimum
Mortgage loans
Period for exercise of call options or interest rate reset options	3 years
Commercial mortgage loans | Maximum
Mortgage loans
Period for exercise of call options or interest rate reset options	10 years
Loan-to-value ratio with participating interest (as a percent)	85.00%