Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Numerator:
Net income attributable to controlling interests	$ 28.0	$ 2.1	$ 80.7	$ 59.4
Less: Total income available to participating unvested securities	0.0	0.0	(0.1)	(0.2)
Total net income attributable to ordinary shares	$ 28.0	$ 2.1	$ 80.6	$ 59.2
Denominator:
Weighted average ordinary shares outstanding (in shares)	91,457,301	108,445,541	94,550,527	108,918,328
Potential ordinary shares:
Restricted stock units (in shares)	38,332	175,580	118,948	185,919
Weighted-average diluted ordinary shares outstanding - diluted (in shares)	91,495,633	108,621,121	94,669,475	109,104,247
Earnings per ordinary share attributable to controlling interests:
Basic (in dollars per share)	$ 0.31	$ 0.02	$ 0.85	$ 0.54
Diluted (in dollars per share)	$ 0.31	$ 0.02	$ 0.85	$ 0.54
Employee options not included in computation of diluted EPS (in shares)	8,970,000		8,970,000