OTHER ASSETS, NET - Schedule of other assets, net (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Finite-Lived Intangible Assets
Less accumulated depreciation and amortization	$ (59.8)		$ (59.8)		$ (57.2)
Data processing software, net	26.8		26.8		29.7
Other assets	34.0		34.0		21.9
Data processing software and other assets, net	60.8		60.8		51.6
Notes receivable	21.1		21.1		9.2
Amortization	30.1	$ 34.2	62.6	$ 71.7
Software development work in progress
Finite-Lived Intangible Assets
Software	0.7		0.7		2.6
Data processing software
Finite-Lived Intangible Assets
Software	85.9		85.9		$ 84.3
Amortization	$ 1.7	$ 3.4	$ 3.5	$ 6.9

The aggregate expense charged against earnings to allocate the cost of intangible assets (nonphysical assets not used in production) in a systematic and rational manner to the periods expected to benefit from such assets. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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