INVESTMENTS IN VARIABLE INTEREST ENTITIES - SCHEDULE OF INVESTMENTS CLASSIFIED BY CONTRACTUAL MATURITY DATE (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2021	Jan. 01, 2020
Amortized cost
Due in one year or less	$ 112.0
Due after one year through five years	1,913.7
Due after five years through ten years	2,098.9
Total	23,384.2
Estimated fair value
Due in one year or less	110.8
Due after one year through five years	1,790.2
Due after five years through ten years	1,910.4
Total	20,353.4	$ 24,805.4	$ 21,293.1
Investments held by variable interest entities - corporate securities
Amortized cost
Due in one year or less	11.4
Due after one year through five years	732.9
Due after five years through ten years	389.9
Total	1,134.2
Estimated fair value
Due in one year or less	9.4
Due after one year through five years	699.0
Due after five years through ten years	369.2
Total	$ 1,077.6