Income Taxes - Schedule of Pre-Tax Income (Loss) and Effective Income Tax Rates (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (21.6)	$ 100.1
Effective Tax Rate	12.80%	8.90%
Bermuda [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (21.7)	$ 32.0
Effective Tax Rate	0.00%	0.00%
United States [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ (10.7)	$ 69.4
Effective Tax Rate	55.00%	14.40%
United Kingdom [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 1.7	$ (3.5)
Effective Tax Rate	183.20%	31.50%
Belgium [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.0	$ 0.0
Effective Tax Rate	68.80%	30.80%
Brazil [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 2.2	$ 1.8
Effective Tax Rate	0.00%	0.00%
United Arab Emirates [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.9	$ 0.2
Effective Tax Rate	0.00%	0.00%
Ireland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.0	$ 0.0
Effective Tax Rate	0.00%	0.00%
Italy [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 3.4	$ (0.7)
Effective Tax Rate	0.00%	0.00%
Malta [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 2.6	$ 0.9
Effective Tax Rate	0.00%	0.00%
Luxembourg [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.0	$ 0.0
Effective Tax Rate	0.00%	0.00%
Switzerland [Member]
Income Tax Examination [Line Items]
Pre-Tax Income (Loss)	$ 0.0	$ 0.0
Effective Tax Rate	0.00%	0.00%