Earnings Per Share (Details) - USD ($) $ / shares in Units, $ 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 (Loss) Attributable to Parent	$ 74.3	$ 83.0	$ 21.6	$ 61.1	$ 18.8	$ 54.2	$ 2.5	$ 54.8	$ 223.9	$ 136.4	$ 4.2
Less: Total income available to participating unvested securities									(0.1)	(0.4)	(0.2)
Total net income attributable to common stock									$ 223.8	$ 136.0	$ 4.0
Denominator:
Weighted-average shares outstanding—basic (in shares)	85,900,000	90,000,000.0	91,500,000	97,600,000	105,600,000	106,400,000	108,400,000	109,400,000	91,205,412	107,431,821	110,708,598
Restricted stock units (in shares)									63,540	191,371	672,544
Weighted-average shares outstanding—diluted (in shares)	85,900,000	90,000,000.0	91,500,000	97,800,000	105,800,000	106,500,000	108,600,000	109,600,000	91,268,952	107,623,192	111,381,142
Earnings per share of common stock attributable to controlling interests:
Earnings per ordinary share attributable to controlling interest - Basic (in dollars per share)	$ 0.79	$ 0.84	$ 0.31	$ 0.54	$ 0.22	$ 0.51	$ 0.02	$ 0.52	$ 2.45	$ 1.27	$ 0.04
Earnings per ordinary share attributable to controlling interests - Diluted (in dollars per share)	$ 0.79	$ 0.84	$ 0.31	$ 0.54	$ 0.22	$ 0.51	$ 0.02	$ 0.52	$ 2.45	$ 1.26	$ 0.04
Employee options excluded from computation of earnings per share (in shares)									8,970,000	6,900,000