INVESTMENTS - SUMMARY OF CHANGES IN THE ALLOWANCE FOR CURRENT EXPECTED CREDIT LOSSES RELATED TO MORTGAGE LOANS (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Financing Receivable, Allowance for Credit Loss [Roll Forward]
Allowance for credit losses at beginning of period	$ 8.0	$ 5.6
Current period provision for expected credit losses	0.4	(0.5)
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 end of period	$ 8.4	$ 5.1