INTANGIBLE ASSETS AND GOODWILL - Finite Lived Assets and Indefinite Lived Assets (Details) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018
Schedule of Finite and Indefinite-lived Intangible Assets
Finite lived assets, gross	$ 603.4	$ 709.3
Accumulated Amortization	(451.3)	(493.1)
Finite lived assets, net	152.1	216.2
Total Intangible Assets
Gross Assets	604.6	710.5
Accumulated Amortization	(451.3)	(493.1)
Net	153.3	217.4
Tradenames
Indefinite Lived Assets
Indefinite lived assets	1.2	1.2
Total Intangible Assets
Net	1.2	1.2
Customer contracts and lists
Schedule of Finite and Indefinite-lived Intangible Assets
Finite lived assets, gross	325.1	339.5
Accumulated Amortization	(278.7)	(244.4)
Finite lived assets, net	$ 46.4	95.1
Amortization Life and Method
Useful life	7 years
Total Intangible Assets
Accumulated Amortization	$ (278.7)	$ (244.4)
Customer contracts and lists \| Minimum
Amortization Life and Method
Useful life		3 years
Customer contracts and lists \| Maximum
Amortization Life and Method
Useful life		7 years
Premium on purchased credit card portfolios
Schedule of Finite and Indefinite-lived Intangible Assets
Finite lived assets, gross	192.6	$ 286.0
Accumulated Amortization	(93.2)	(172.9)
Finite lived assets, net	99.4	113.1
Total Intangible Assets
Accumulated Amortization	$ (93.2)	$ (172.9)
Premium on purchased credit card portfolios \| Minimum
Amortization Life and Method
Useful life	1 year	3 years
Premium on purchased credit card portfolios \| Maximum
Amortization Life and Method
Useful life	13 years	13 years
Collector database
Schedule of Finite and Indefinite-lived Intangible Assets
Finite lived assets, gross	$ 53.9	$ 51.3
Accumulated Amortization	(52.9)	(49.9)
Finite lived assets, net	$ 1.0	$ 1.4
Amortization Life and Method
Useful life	5 years	5 years
Total Intangible Assets
Accumulated Amortization	$ (52.9)	$ (49.9)
Tradenames
Schedule of Finite and Indefinite-lived Intangible Assets
Finite lived assets, gross	31.8	32.5
Accumulated Amortization	(26.5)	(25.9)
Finite lived assets, net	5.3	6.6
Total Intangible Assets
Accumulated Amortization	$ (26.5)	$ (25.9)
Tradenames \| Minimum
Amortization Life and Method
Useful life	8 years	8 years
Tradenames \| Maximum
Amortization Life and Method
Useful life	15 years	15 years

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Useful life of finite-lived intangible assets, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

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Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

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