Earnings Per Share - Schedule of Basic and Diluted Earnings Per Share (Details) - USD ($) shares in Millions, $ in Millions	3 Months Ended
Mar. 31, 2019	Mar. 31, 2018
Numerator
Net income (loss) (controlling interest)	$ (200.8)	$ 153.0
Interest expense on junior convertible securities, net of taxes	0.0	4.7
Net income (loss) (controlling interest), as adjusted	$ (200.8)	$ 157.7
Denominator
Average shares outstanding (basic) (in shares)	51.9	54.6
Effect of dilutive instruments:
Stock options and restricted stock units (in shares)	0.0	0.2
Junior convertible securities (in shares)	0.0	2.2
Average shares outstanding (diluted) (in shares)	51.9	57.0

Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of convertible debt securities using the if-converted method.

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