Commitments and Contingencies - Schedule of commitments under operating leases (Details) $ in Millions	Dec. 31, 2018 USD ($)
Operating Leased Assets [Line Items]
2019	$ 10.4
2020	3.8
2021	3.4
2022	2.2
2023	1.5
Thereafter	4.1
Total	25.4
Facilities
Operating Leased Assets [Line Items]
2019	4.2
2020	3.6
2021	3.3
2022	2.2
2023	1.5
Thereafter	4.1
Total	18.9
Equipment
Operating Leased Assets [Line Items]
2019	6.2
2020	0.2
2021	0.1
2022	0.0
2023	0.0
Thereafter	0.0
Total	$ 6.5