Equity - Reclassification Out of Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2019	Mar. 31, 2019	Jun. 30, 2020	Jun. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales and services	$ 54.7		$ 80.2		$ 108.6	$ 145.8
Total before tax	2.2		(18.1)		4.4	(39.1)
Net (loss)/income	0.2	$ 1.9	(15.5)	$ (16.9)	2.1	(32.4)
Income tax (benefit)/expense	$ (2.0)		2.6		$ (2.3)	6.7
Amounts Reclassified from Acccumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total before tax			(0.3)			(0.7)
Net (loss)/income			(0.3)			(0.7)
Income tax (benefit)/expense			0.1			0.1
Foreign currency contracts | Derivative instruments | Amounts Reclassified from Acccumulated Other Comprehensive Loss
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Costs of sales and services			$ (0.3)			$ (0.7)