Earnings per Share (EPS) - Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
EPS numerator:
Loss from continuing operations, net of income taxes	$ (23.0)	$ (1,545.3)	$ (100.7)	$ (1,674.6)
Less: Net income (loss) attributable to noncontrolling interests	3.3	(3.4)	3.7	(5.2)
Loss from continuing operations attributable to common stockholders	(26.3)	(1,541.9)	(104.4)	(1,669.4)
Loss from discontinued operations, net of income taxes	(2.3)	(2.3)	(4.3)	(4.5)
Net loss attributable to common stockholders	$ (28.6)	$ (1,544.2)	$ (108.7)	$ (1,673.9)
EPS denominator:
Weighted average shares outstanding — basic and diluted	101.2	97.9	99.8	97.5
Basic EPS attributable to common stockholders:
Basic loss per share	$ (0.28)	$ (15.78)	$ (1.09)	$ (17.16)
Basic and diluted EPS attributable to common stockholders:
Loss from continuing operations	(0.26)	(15.76)	(1.05)	(17.12)
Loss from discontinued operations	(0.02)	(0.02)	(0.04)	(0.04)
Net loss attributable to common stockholders	$ (0.28)	$ (15.78)	$ (1.09)	$ (17.16)