REVISION OF PREVIOUSLY ISSUED QUARTERLY FINANCIAL STATEMENTS (UNAUDITED) - Equity Statement and Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended	9 Months Ended	12 Months Ended
	Dec. 31, 2022	Sep. 30, 2022	Jun. 30, 2022	Mar. 31, 2022	Jun. 30, 2022	Sep. 30, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity	$ 277.1	$ 321.8	$ 381.3	$ 467.6	$ 381.3	$ 321.8	$ 277.1	$ 536.4	$ 1,032.4	$ (374.0)
Statement of Cash Flows [Abstract]
Net loss	(58.3)	(66.4)	(95.5)	(77.5)	(173.0)	(239.4)	(297.7)	(521.1)	(363.0)
Other assets				6.0	(3.8)	(2.0)	(7.5)	0.8	(21.7)
Net cash used in operating activities				(51.2)	(104.9)	(163.9)	(210.6)	(403.4)	(287.2)
Accumulated Loss
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity	$ (1,567.8)	(1,509.5)	(1,443.1)	(1,347.6)	(1,443.1)	(1,509.5)	(1,567.8)	(1,270.1)	(748.0)	$ (385.0)
Statement of Cash Flows [Abstract]
Net loss							$ (297.7)	$ (521.1)	$ (363.0)
As reported
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity		330.9	388.0	468.7	388.0	330.9
Statement of Cash Flows [Abstract]
Net loss		(64.0)	(89.9)	(76.4)	(166.3)	(230.3)
Other assets				4.9	(10.5)	(11.1)
Net cash used in operating activities				(51.2)	(104.9)	(163.9)
As reported | Accumulated Loss
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity		(1,500.4)	(1,436.4)	(1,346.5)	(1,436.4)	(1,500.4)
Adjustments
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity		(9.1)	(6.7)	(1.1)	(6.7)	(9.1)
Statement of Cash Flows [Abstract]
Net loss		(2.4)	(5.6)	(1.1)	(6.7)	(9.1)
Other assets				1.1	6.7	9.1
Net cash used in operating activities				0.0	0.0	0.0
Adjustments | Accumulated Loss
Statement of Stockholders' Equity [Abstract]
Total stockholders’ equity		$ (9.1)	$ (6.7)	$ (1.1)	$ (6.7)	$ (9.1)