INVESTMENTS - VALUATION ALLOWANCE FOR MORTGAGE LOANS (Details) - USD ($)	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
March 31, Individually Evaluated for Impairment	$ 7,000,000		$ 8,000,000
Commercial Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance, January 1,	8,000,000	$ 8,000,000
Charge-offs	0	0
Recoveries	(1,000,000)	0
Provision	0	0
Ending balance, March 31,	7,000,000	8,000,000
Financing Receivable, Allowance for Credit Loss, Additional Information [Abstract]
March 31, Individually Evaluated for Impairment	7,000,000	$ 8,000,000
Agricultural Mortgage Loans
Financing Receivable, Allowance for Credit Losses [Roll Forward]
Beginning balance, January 1,	0
Ending balance, March 31,	$ 0