Leases - Assets and Liabilities, Lessee (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Operating Leases
Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Other assets	Other assets
Operating lease right-of-use assets	$ 119.1	$ 136.2
Operating Lease, Liability, Current, Statement of Financial Position [Extensible List]	Accounts payable and other current liabilities (includes affiliate payables of $4.1 and $0.5, respectively)	Accounts payable and other current liabilities (includes affiliate payables of $4.1 and $0.5, respectively)
Current operating lease liabilities	$ 45.4	$ 47.1
Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Other liabilities	Other liabilities
Non-current operating lease liabilities	$ 87.8	$ 106.4
Operating Lease, Liability	$ 133.2	$ 153.5
Finance Leases
Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List]	Properties, less accumulated depreciation of $3,507.2 and $3,416.4, respectively	Properties, less accumulated depreciation of $3,507.2 and $3,416.4, respectively
Finance lease right-of-use assets	$ 61.5	$ 60.5
Finance Lease, Liability, Current, Statement of Financial Position [Extensible List]	Debt, Current	Debt, Current
Current finance lease liabilities	$ 4.6	$ 4.1
Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List]	Long-term debt	Long-term debt
Non-current finance lease liabilities	$ 62.6	$ 59.9
Total finance lease liabilities	$ 67.2	$ 64.0
Weighted-Average Remaining Lease Term (Years)
Operating leases, weighted-average remaining lease term (in years)	4 years 1 month 6 days
Finance leases, weighted average remaining lease term (in years)	11 years 10 months 24 days
Weighted-Average Discount Rate
Operating leases, weighted average discount rate	3.50%
Finance leases, weighted average discount rate	6.50%