INVESTMENTS IN VARIABLE INTEREST ENTITIES (SUMMARY OF VARIABLE INTEREST ENTITIES BY CONTRACTUAL MATURITY) (Details) $ in Millions	Dec. 31, 2016 USD ($)
Variable Interest Entity [Line Items]
Total, Amortized Cost	$ 1,708.6
Total, Estimated Fair Value	1,724.3
Amortized Cost [Member]
Variable Interest Entity [Line Items]
Due in one year or less	20.5
Due after one year through five years	846.5
Due after five years through ten years	841.6
Total, Amortized Cost	1,708.6
Due in one year or less	10.5
Due after one year through five years	175.2
Due after five years through ten years	55.8
Total, Amortized Cost	241.5
Estimated Fair Value [Member]
Variable Interest Entity [Line Items]
Due in one year or less	20.0
Due after one year through five years	853.1
Due after five years through ten years	851.2
Total, Estimated Fair Value	1,724.3
Due in one year or less	9.9
Due after one year through five years	172.5
Due after five years through ten years	55.3
Total, Estimated Fair Value	$ 237.7