Investments (Details) - USD ($) $ in Thousands			1 Months Ended		3 Months Ended
	Nov. 22, 2016	Jul. 05, 2016	Nov. 30, 2016	Jul. 31, 2016	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Schedule of Equity Method Investments [Line Items]
Capital investments					$ 125,323		$ 125,059
Earnings from equity investments					4,272	$ 482
Amortization of intangible assets					3,365	3,412
Distributions received					6,992	$ 2,010
Carnero Gathering, Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)		50.00%		50.00%
Payments to acquire interest in joint venture		$ 37,000		$ 37,000	46,400
Assumption of capital commitments in joint venture		$ 7,400		7,400
Capital investments					100
Earnout payments					0
Earnings from equity investments					2,200
Distributions received					2,600
Carnero Gathering, Joint Venture | Customer Relationships
Schedule of Equity Method Investments [Line Items]
Intangible asset, fair value				13,000
Amortization of intangible assets					200
Carnero Processing Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)	50.00%		50.00%
Payments to acquire interest in joint venture	$ 55,500		$ 55,500		200
Assumption of capital commitments in joint venture	$ 24,500		24,500
Capital investments					74,900
Earnings from equity investments					2,300
Distributions received					$ 4,400
Sanchez Energy
Schedule of Equity Method Investments [Line Items]
Payments to acquire interest in joint venture			25,000
Assumption of capital commitments in joint venture			24,200
Sanchez Energy | Carnero Gathering, Joint Venture
Schedule of Equity Method Investments [Line Items]
Capital investments				$ 26,000
Sanchez Energy | Carnero Processing Joint Venture
Schedule of Equity Method Investments [Line Items]
Capital investments			$ 48,000
Targa | Carnero Gathering, Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)				50.00%
Targa | Carnero Processing Joint Venture
Schedule of Equity Method Investments [Line Items]
Ownership interest (as a percent)			50.00%