MORTGAGE LOANS (Details 2) (Commercial mortgage loans, USD $)	3 Months Ended	12 Months Ended
	Mar. 31, 2013 item	Dec. 31, 2012
Commercial mortgage loans
Mortgage loans
Mortgage loans having participation feature	$ 736,900,000	$ 817,300,000
Maximum nonperforming mortgage loans, foreclosed properties and restructured loans to invested assets (as a percent)	0.06%
Maximum nonperforming mortgage loans, foreclosed properties and restructured loans pursuant to pooling and servicing agreement	21,200,000
Number of loan categories	2
Nonperforming loans not subject to a pooling and servicing agreement	14,300,000
Loans subject to a pooling and servicing agreement which are either nonperforming or restructured	6,900,000
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	2,875,000	6,475,000
Charge offs		(9,840,000)
Recoveries		(628,000)
Provision	1,170,000	6,868,000
Ending balance	$ 4,045,000	$ 2,875,000