STOCKHOLDERS' EQUITY Stock - Compensation Plans (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Stock-based compensation expense	$ 4.7	$ 11.3
Cost of operations.
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Stock-based compensation expense	2.7	6.7
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Stock-based compensation expense	$ 2.0	4.6
Discontinued Operations, Held-for-sale | Epsilon
Employee Service Share-based Compensation, Allocation of Recognized Period Costs
Stock-based compensation expense		$ 9.8