Maturities of lease liabilities (Details) $ in Millions	Mar. 31, 2020 USD ($)
Leases [Abstract]
2020 (excluding the three months ended March 31, 2020)	$ 58.1
2021	50.3
2022	29.9
2023	17.4
2024	12.7
Thereafter	23.5
Total	191.9
Less: Present value discount	(38.4)
Lease liability	153.5
2020 (excluding the three months ended March 31, 2020)	1.2
2021	1.6
2022	0.7
2023	0.2
2024	0.1
Thereafter	0.1
Total	3.9
Less: Present value discount	(0.6)
Lease liability	$ 3.3