INVESTMENTS - SUMMARY OF CHANGES IN THE ALLOWANCE FOR CURRENT EXPECTED CREDIT LOSSES RELATED TO MORTGAGE LOANS (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2020
Mortgage loans
Allowance for credit losses at beginning	$ 11.6	$ 6.7
Current period provision for expected credit losses	0.6	5.5
Initial allowance recognized for purchased financial assets with credit deterioration	0.0	0.0
Write-offs charged against the allowance	0.0	0.0
Recoveries of amounts previously written off	0.0	0.0
Allowance for credit losses at ending	$ 12.2	$ 12.2