Related Party Transactions - Schedule of Reimbursement from Parent (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Related Party Transaction [Line Items]
Receivable from Parent	$ 1.9	$ 0.0	$ 0.2
Shell Pipeline Company L P
Related Party Transaction [Line Items]
Cash received		11.7	15.8	$ 2.8
Receivable from Parent		(0.3)	0.3	$ 0.2
Total reimbursements	$ 11.4	$ 16.1	$ 3.0