Earnings Per Common Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Numerator:
Net income from continuing operations, net of loss attributable to non-controlling interests	$ 46.7	$ 72.4	$ 42.7	$ 29.0	$ 19.1	$ 44.1	$ 26.6	$ 25.6	$ 190.9	$ 118.3	$ 182.3
Denominator:
Denominator for basic earnings per common share—weighted average shares									54.5	54.4	54.0
Effect of dilutive securities:
Employee stock based compensation (in shares)									0.9	0.7	0.7
Denominator for diluted earnings per common share—adjusted weighted average shares (in shares)									55.4	55.1	54.7
Earnings per share for continuing operations, basic (in dollars per share)	$ 0.87	$ 1.33	$ 0.78	$ 0.53	$ 0.35	$ 0.83	$ 0.52	$ 0.48	$ 3.50	$ 2.17	$ 3.37
Earnings per share for continuing operations, diluted (in dollars per share)	$ 0.85	$ 1.30	$ 0.76	$ 0.52	$ 0.35	$ 0.82	$ 0.52	$ 0.47	$ 3.45	$ 2.15	$ 3.33
Shares excluded from diluted earnings per common share computation as anti-dilutive (in shares)									1.1	1.5	1.3