Commitments and Contingencies, Operating Leases (Details) $ in Millions	Jun. 30, 2019 USD ($)
Operating Leases [Abstract]
ROU asset carrying value	$ 227.6
Lease liability carrying value	229.5
Lease liability, current	38.6
Lease liability, noncurrent	190.9
Storage and Pipeline Facilities [Member]
Operating Leases [Abstract]
ROU asset carrying value	144.3	[1]
Lease liability carrying value	$ 145.0	[2]
Weighted-average remaining term	16 years
Weighted-average discount rate	4.30%	[3]
Transportation Equipment [Member]
Operating Leases [Abstract]
ROU asset carrying value	$ 56.2	[1]
Lease liability carrying value	$ 58.7	[2]
Weighted-average remaining term	4 years
Weighted-average discount rate	3.60%	[3]
Office Building and Warehouse Space [Member]
Operating Leases [Abstract]
ROU asset carrying value	$ 27.1	[1]
Lease liability carrying value	$ 25.8	[2]
Weighted-average remaining term	3 years
Weighted-average discount rate	3.50%	[3]

[1] ROU asset amounts are a component of “Other assets” on our consolidated balance sheet.

[2] At June 30, 2019, lease liabilities of $38.6 million and $190.9 million were included within “Other current liabilities” and “Other liabilities,” respectively.

[3] The discount rate for each category of assets represents the weighted average of either (i) the implicit rate applicable to the underlying leases (where determinable) or (ii) our incremental borrowing rate adjusted for collateralization (if the implicit rate is not determinable).  In general, the discount rates are based on either (i) information available at the lease commencement date or (ii) January 1, 2019 for leases existing at the adoption date for ASC 842.