Leases - Operating lease liabilities (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Leases
Current operating lease liabilities	$ 88.0
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent us-gaap:OperatingLeaseLiabilityNoncurrent
Long-term operating lease liabilities	$ 2,234.1	$ 2,301.2
Total operating lease liabilities	$ 2,322.1