Earnings Per Share ("EPS") (Details) - USD ($) shares in Millions, $ in Millions		3 Months Ended		6 Months Ended
		Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Net income (loss) available for common stockholders		$ (57.9)	$ 50.3	$ (51.8)	$ 56.4
Less: Distributions to holders of securities				61.1	103.9
Net income (loss) available for common stockholders, basic and diluted		$ (63.4)	$ 49.7	$ (57.7)	$ 55.3
Weighted average number of shares for basic EPS (shares)		144.4	142.3	144.1	141.5
Dilutive potential shares from grants of RSUs, PRSUs and stock options (shares)	[1]	0.0	0.6	0.0	0.5
Weighted average number of shares for diluted EPS (shares)		144.4	142.9	144.1	142.0
Series A Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Less: Distributions to holders of securities		$ 5.5	$ 0.0	$ 5.5	$ 0.0
Noncontrolling Interest
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Less: Distributions to holders of securities		0.0	0.5	0.4	1.1
Less: Undistributed earnings allocable to Class A equity interests of a subsidiary		$ 0.0	$ 0.1	$ 0.0	$ 0.0
Noncontrolling Interest
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from EPS calculation (shares)		0.9	1.5	1.0	1.6
Stock compensation plan
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from EPS calculation (shares)		1.8	0.1	1.0	0.1
Series A Preferred Stock
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]
Antidilutive securities excluded from EPS calculation (shares)		19.8		9.9

[1] The potential impact of an aggregate 1.8 million granted RSUs, PRSUs and stock options in the three months ended June 30, 2020, 0.1 million granted RSUs, PRSUs and stock options in the three months ended June 30, 2019, 1.0 million granted RSUs, PRSUs and stock options in the six months ended June 30, 2020, and 0.1 million granted RSUs, PRSUs and stock options in the six months ended June 30, 2019, were antidilutive.(b)The potential impact of 19.8 million shares of our common stock issuable upon conversion of our Series A Preferred Stock in the three months ended June 30, 2020, and 9.9 million shares of our common stock issuable upon conversion of our Series A Preferred Stock in the six months ended June 30, 2020, was antidilutive.