DEBT AND OTHER OBLIGATIONS - Schedule of Interest Expense (Details) - USD ($) $ in Millions	1 Months Ended	11 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2015	Dec. 31, 2017	Dec. 31, 2016
Debt Instrument [Line Items]
Debt and subordinated debt securities		$ 58.6	$ 61.3	$ 62.1
Non-recourse funding obligations, other obligations, and repurchase agreements		54.1	171.9	163.7
Total interest expense		$ 112.7	$ 233.2	$ 225.8
Predecessor
Debt Instrument [Line Items]
Debt and subordinated debt securities	$ 8.9
Non-recourse funding obligations, other obligations, and repurchase agreements	4.9
Total interest expense	$ 13.8