REVENUE - Performance Obligation (Details) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($)
REVENUE
Initial application and transition, completed contract, same reporting period	true
Incremental Cost of Obtaining Contract	true
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
REVENUE
Revenue, remaining performance obligation	$ 144.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
REVENUE
Revenue, remaining performance obligation	$ 79.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2022-01-01
REVENUE
Revenue, remaining performance obligation	$ 33.5
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	12 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
REVENUE
Revenue, remaining performance obligation	$ 1.1
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	12 months