Maturities of lease liabilities (Details) $ in Millions	Jun. 30, 2019 USD ($)
Leases [Abstract]
2019 (excluding the three months ended March 31, 2019)	$ 50.3
2020	61.3
2021	39.2
2022	22.9
2023	14.8
Thereafter	25.5
Total	214.0
Less: Present value discount	(48.1)
Lease liability	165.9
2019 (excluding the six months ended June 30, 2019)	0.4
2020	0.9
2021	0.9
2022	0.0
2023	0.0
Thereafter	0.0
Total	2.2
Less: Present value discount	(0.7)
Lease liability	$ 1.5