Related Party Transactions - Schedule of Condensed Combined Statement of Operations (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016		Sep. 30, 2017		Sep. 30, 2016
Related Party Transaction [Line Items]
Operations and maintenance – related parties	$ 8.4	$ 7.5	[1]	$ 26.6	[2]	$ 22.6	[1]
General and administrative – related parties	8.6	7.4	[1]	25.2	[2]	22.3	[1]
Management Agreement
Related Party Transaction [Line Items]
Payment for general administrative services	2.1	1.9		6.1		5.8
Omnibus Agreement
Related Party Transaction [Line Items]
Payment for general administrative services	$ 2.2	$ 2.2		$ 6.4		$ 6.4

[1] Prior period financial information has been retrospectively adjusted for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations.

[2] The financial information for the nine months ended September 30, 2017 reflects adjustments for the acquisition of the Shell Delta, Na Kika and Refinery Gas Pipeline Operations from January 1, 2017 through May 9, 2017.