Leases - Operating lease liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2021	Dec. 31, 2020
Leases
Current operating lease liabilities	$ 95.4
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	us-gaap:AccruedLiabilitiesCurrent us-gaap:OperatingLeaseLiabilityNoncurrent
Long-term operating lease liabilities	$ 2,375.5	$ 2,350.3
Total operating lease liabilities	$ 2,470.9