Income Taxes - Schedule of reconciliation of effective tax rate (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Disclosure [Abstract]
Income/(loss) before income taxes	$ 42.8	$ (210.8)	$ (341.8)
Taxes at the statutory rate	9.0	(44.9)	(119.7)
Adjusted for:
State taxes, net of the federal benefit	(2.9)	(1.2)	8.7
Other permanent adjustments	19.3	11.3	(5.3)
Foreign tax rate differential	0.3	0.5	13.3
Change in valuation allowance	(9.7)	41.1	30.5
Impact of repatriation	12.0	(0.7)	7.7
Uncertain tax positions	4.3	0.7	11.3
Transfer pricing	0.0	0.0	(13.1)
Deferred tax inventory	4.5
Impact of restructuring	6.0
Other, net	(0.2)	(2.6)	7.0
Impact of US tax reform	0.0	(29.2)	(60.9)
Total income tax provision/(benefit)	$ 42.6	$ (25.0)	$ (120.5)