SEGMENT INFORMATION - Revenue by Geographical Region (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues	$ 142.3	$ 143.0	$ 143.7	$ 140.7	$ 178.7	$ 185.8	$ 218.3	$ 190.7	$ 569.7	$ 772.4	$ 801.8
United States [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									275.7	327.7	307.6
United Kingdom [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									294.0	444.7	493.2
Japan [Member]
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenues									$ 0.0	$ 0.0	$ 1.0