Maturities of lease liabilities (Details) $ in Millions	Sep. 30, 2020 USD ($)
Leases [Abstract]
2020 (excluding the nine months ended September 30, 2020)	$ 25.5
2021	55.1
2022	34.6
2023	21.4
2024	15.3
Thereafter	25.1
Total	177.0
Less: Present value discount	(35.7)
Lease liability	141.3
2020 (excluding the nine months ended September 30, 2020)	0.6
2021	2.0
2022	1.3
2023	0.6
2024	0.5
Thereafter	0.8
Total	5.8
Less: Present value discount	(0.9)
Lease liability	$ 4.9