REVENUE - Performance Obligation (Details) - LoyaltyOne $ in Millions	Mar. 31, 2020 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2020-01-01
REVENUE
Revenue, remaining performance obligation	$ 106.8
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	9 months
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-01-01
REVENUE
Revenue, remaining performance obligation	$ 83.3
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	$ 40.8
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	$ 4.3
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction
Revenue, expected timing of satisfaction of remaining performance	12 months