Organization and Nature of Operations - Narrative (Details) $ / shares in Units, bbl / d in Thousands, bbl in Thousands, $ in Thousands					9 Months Ended
	Jun. 26, 2017	Jun. 20, 2017 USD ($) $ / shares shares	Apr. 03, 2017 USD ($) bbl / d mi bbl	Sep. 20, 2016 $ / shares shares	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
Subsidiary, Sale of Stock [Line Items]
Stock price ($ per share) | $ / shares		$ 44.45
Gross proceeds		$ 142,600
Net proceeds		$ 138,100			$ 138,084	$ 0
White Cliffs Interest
Subsidiary, Sale of Stock [Line Items]
Non-controlling ownership				3.33%
Colorado River DevCo
Subsidiary, Sale of Stock [Line Items]
Ownership acquired		20.00%
Ownership	100.00%
Blanco River DevCo
Subsidiary, Sale of Stock [Line Items]
Ownership acquired		15.00%
Ownership	40.00%
Private Placement
Subsidiary, Sale of Stock [Line Items]
Sold (in units) | shares		3,525,000
Offering costs		$ 4,500
Common Units | IPO
Subsidiary, Sale of Stock [Line Items]
Sold (in units) | shares				14,375,000
Price ($ per unit) | $ / shares				$ 22.50
Price, net ($ per unit) | $ / shares				$ 21.20625
Common Units | Over-Allotment Option
Subsidiary, Sale of Stock [Line Items]
Sold (in units) | shares				1,875,000
Blanco River and Colorado River DevCos
Subsidiary, Sale of Stock [Line Items]
Consideration		270,000
Payments to acquire		$ 245,000
Equity issued (units) | shares		562,430
Corporate Joint Venture | Advantage Pipeline
Subsidiary, Sale of Stock [Line Items]
Consideration			$ 133,000
Payment to acquire interest in joint venture			$ 66,800
Length of pipeline (in miles) | mi			70
Shipping capacity per day (in barrels) | bbl / d			150
Storage capacity (in barrels) | bbl			490
Corporate Joint Venture | Plains All American Pipeline | Advantage Pipeline
Subsidiary, Sale of Stock [Line Items]
Ownership interest, equity method			50.00%