Earnings per Share (EPS) - Calculation of Basic and Diluted EPS (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
EPS numerator:
(Loss) income from continuing operations, net of income taxes	$ (64.8)	$ (74.3)	$ (1,739.4)	$ 101.9
Less: Net income (loss) attributable to noncontrolling interests	0.1	4.7	(5.1)	12.8
(Loss) income from continuing operations attributable to common stockholders	(64.9)	(79.0)	(1,734.3)	89.1
Loss from discontinued operations, net of income taxes	(2.3)	(3.8)	(6.8)	(10.6)
Net (loss) income attributable to common stockholders	$ (67.2)	$ (82.8)	$ (1,741.1)	$ 78.5
EPS denominator:
Weighted average shares outstanding — basic (in shares)	97.9	102.2	97.6	105.9
Impact of dilutive securities (in shares)	0.0	0.0	0.0	1.5
Weighted average shares outstanding — diluted (in shares)	97.9	102.2	97.6	107.4
Basic EPS attributable to common stockholders:
(Loss) income from continuing operations (in dollars per share)	$ (0.66)	$ (0.77)	$ (17.76)	$ 0.84
Loss from discontinued operations (in dollars per share)	(0.03)	(0.04)	(0.07)	(0.10)
Basic (loss) income per share (in dollars per share)	(0.69)	(0.81)	(17.83)	0.74
Diluted EPS attributable to common stockholders:
(Loss) income from continuing operations (in dollars per share)	(0.66)	(0.77)	(17.76)	0.83
Loss from discontinued operations (in dollars per share)	(0.03)	(0.04)	(0.07)	(0.10)
Diluted (loss) income per share (in dollars per share)	$ (0.69)	$ (0.81)	$ (17.83)	$ 0.73