SIGNIFICANT ACCOUNTING POLICIES - DEFERRED ACQUISITION COSTS (Details)	12 Months Ended
	Dec. 31, 2017	Jun. 30, 2015	Dec. 31, 2014
Accounting Policies [Abstract]
Mean (RTM) assumption		7.00%	9.00%
Average annual rate of return, gross	7.00%
Average annual rate of return, net	4.70%
Future annual rate of return, gross, maximum	15.00%
Future annual rate of return, gross, minimum	12.70%
Future annual rate of return, net, maximum	0.00%
Future annual rate of return, net, minimum	(2.30%)
Future annual rate of return assumption duration maximum	5 years
Assumed actual future annual rate of return resulting in acceleration of deferred acquisition costs amortization	15.00%
Assumed actual future annual rate of return resulting in decelaration of deferred acquisition costs amortization	0.00%
Assumed average investment yield excluding policy loans, high end	4.70%
Assumed average investment yield excluding policy loans, low end	4.30%
Period used In assumed average investment yield excluding policy loans	7 years