The estimated number of months an AIR MILES reward mile remains active and unused.

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REVENUE (Details) $ in Millions	3 Months Ended								12 Months Ended
REVENUE (Details) $ in Millions	Dec. 31, 2019 USD ($)	Sep. 30, 2019 USD ($)	Jun. 30, 2019 USD ($)	Mar. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Sep. 30, 2018 USD ($)	Jun. 30, 2018 USD ($)	Mar. 31, 2018 USD ($)	Dec. 31, 2019 USD ($) item segment	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016
Disaggregation of revenue
Number of segments \| segment									2
Revenue from contracts with customers									$ 840.2	$ 960.1
Finance charges, net									4,728.5	4,694.9	$ 4,171.9
Investment income									12.6	11.6
Total revenue	$ 1,461.0	$ 1,437.6	$ 1,348.5	$ 1,334.2	$ 1,464.5	$ 1,423.2	$ 1,397.2	$ 1,381.7	$ 5,581.3	$ 5,666.6	$ 5,474.7
Number of performance obligations \| item									3
Estimated breakage rate	20.00%				20.00%				20.00%	20.00%	20.00%
Estimated Life of an AIR MILES reward mile									38 months	38 months	38 months	42 months
Coalition loyalty program
Disaggregation of revenue
Revenue from contracts with customers									$ 290.1	$ 352.3
Short-term loyalty programs
Disaggregation of revenue
Revenue from contracts with customers									635.5	613.8
Servicing fees, net
Disaggregation of revenue
Revenue from contracts with customers									(180.7)	(97.3)
Other
Disaggregation of revenue
Revenue from contracts with customers									95.3	91.3
United States
Disaggregation of revenue
Total revenue									4,588.3	4,621.3	$ 4,192.5
Canada
Disaggregation of revenue
Total revenue									352.2	411.3	726.6
Europe, Middle East and Africa
Disaggregation of revenue
Total revenue									449.1	463.2	411.4
Asia Pacific
Disaggregation of revenue
Total revenue									121.7	122.0	129.2
Other
Disaggregation of revenue
Total revenue									70.0	48.8	15.0
Operating segment \| LoyaltyOne
Disaggregation of revenue
Revenue from contracts with customers									1,020.5	1,056.8
Investment income									12.6	11.6
Total revenue									1,033.1	1,068.4	1,303.5
Operating segment \| LoyaltyOne \| Coalition loyalty program
Disaggregation of revenue
Revenue from contracts with customers									290.1	352.3
Operating segment \| LoyaltyOne \| Short-term loyalty programs
Disaggregation of revenue
Revenue from contracts with customers									635.5	613.8
Operating segment \| LoyaltyOne \| Other
Disaggregation of revenue
Revenue from contracts with customers									94.9	90.7
Operating segment \| LoyaltyOne \| United States
Disaggregation of revenue
Total revenue									40.1	23.1
Operating segment \| LoyaltyOne \| Canada
Disaggregation of revenue
Total revenue									352.2	411.3
Operating segment \| LoyaltyOne \| Europe, Middle East and Africa
Disaggregation of revenue
Total revenue									449.1	463.2
Operating segment \| LoyaltyOne \| Asia Pacific
Disaggregation of revenue
Total revenue									121.7	122.0
Operating segment \| LoyaltyOne \| Other
Disaggregation of revenue
Total revenue									70.0	48.8
Operating segment \| Card Services
Disaggregation of revenue
Revenue from contracts with customers									(180.7)	(97.3)
Finance charges, net									4,728.5	4,694.9
Total revenue									4,547.8	4,597.6	4,170.6
Operating segment \| Card Services \| Servicing fees, net
Disaggregation of revenue
Revenue from contracts with customers									(180.7)	(97.3)
Operating segment \| Card Services \| United States
Disaggregation of revenue
Total revenue									4,547.8	4,597.6
Corporate/Other
Disaggregation of revenue
Revenue from contracts with customers									0.4	0.6
Total revenue									0.4	0.6	$ 0.6
Corporate/Other \| Other
Disaggregation of revenue
Revenue from contracts with customers									0.4	0.6
Corporate/Other \| United States
Disaggregation of revenue
Total revenue									$ 0.4	$ 0.6
Minimum \| Short-term loyalty programs
Disaggregation of revenue
Typical term of short-term loyalty programs									84 days
Maximum \| Short-term loyalty programs
Disaggregation of revenue
Typical term of short-term loyalty programs									140 days
Typical contract term of the short-term loyalty programs									1 year