Maturities of lease liabilities (Details) $ in Millions	Sep. 30, 2019 USD ($)
Leases [Abstract]
2019 (excluding the three months ended March 31, 2019)	$ 29.6
2020	66.8
2021	42.5
2022	26.4
2023	16.6
Thereafter	37.3
Total	219.2
Less: Present value discount	(49.3)
Lease liability	169.9
2019 (excluding the nine months ended September 30, 2019)	0.1
2020	0.9
2021	0.9
2022	0.0
2023	0.0
Thereafter	0.0
Total	1.9
Less: Present value discount	(0.6)
Lease liability	$ 1.3