Maturities of lease liabilities (Details) $ in Millions	Jun. 30, 2020 USD ($)
Leases [Abstract]
2020 (excluding the six months ended June 30, 2020)	$ 42.2
2021	52.0
2022	31.4
2023	18.9
2024	13.7
Thereafter	24.1
Total	182.3
Less: Present value discount	(36.0)
Lease liability	146.3
2020 (excluding the six months ended June 30, 2020)	1.1
2021	2.1
2022	1.2
2023	0.5
2024	0.5
Thereafter	0.7
Total	6.1
Less: Present value discount	(1.0)
Lease liability	$ 5.1