Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019		Mar. 31, 2018	[1]
Schedule of Equity Method Investments [Line Items]
Balance	[1]	$ 1,092,088
Acquisitions		92,546
Equity income, net	[2]	57,992		$ 30,229
Contributions		36,543	[3]	0
Distributions		(54,221)		(31,576)
Distributions in excess of cumulative earnings		(7,792)	[4]	$ (8,850)
Balance		1,217,156
Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance		2,259
Acquisitions		0
Equity income, net		(573)
Contributions	[3]	0
Distributions		0
Distributions in excess of cumulative earnings	[4]	(237)
Balance		1,449
White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance		43,020
Acquisitions		0
Equity income, net		3,225
Contributions	[3]	1,845
Distributions		(3,079)
Distributions in excess of cumulative earnings	[4]	(935)
Balance		44,076
Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance		37,841
Acquisitions		0
Equity income, net		121
Contributions	[3]	0
Distributions		(607)
Distributions in excess of cumulative earnings	[4]	(671)
Balance		36,684
Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance		104,949
Acquisitions		0
Equity income, net		7,127
Contributions	[3]	0
Distributions		(4,500)
Distributions in excess of cumulative earnings	[4]	0
Balance		107,576
Texas Express Gathering [Member]
Schedule of Equity Method Investments [Line Items]
Balance		19,358
Acquisitions		0
Equity income, net		830
Contributions	[3]	0
Distributions		(835)
Distributions in excess of cumulative earnings	[4]	(316)
Balance		19,037
Texas Express Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance		193,198
Acquisitions		0
Equity income, net		8,665
Contributions	[3]	6,000
Distributions		(9,865)
Distributions in excess of cumulative earnings	[4]	0
Balance		197,998
Front Range Pipeline [Member]
Schedule of Equity Method Investments [Line Items]
Balance		176,436
Acquisitions		0
Equity income, net		7,125
Contributions	[3]	0
Distributions		(6,480)
Distributions in excess of cumulative earnings	[4]	0
Balance		177,081
Whitethorn LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance		161,858
Acquisitions		0
Equity income, net		21,860
Contributions	[3]	3,228
Distributions		(17,058)
Distributions in excess of cumulative earnings	[4]	(5,213)
Balance		164,675
Cactus II [Member]
Schedule of Equity Method Investments [Line Items]
Balance		106,360
Acquisitions		0
Equity income, net		0
Contributions	[3]	17,791
Distributions		0
Distributions in excess of cumulative earnings	[4]	0
Balance		124,151
Capitalized interest		1,500
Saddlehorn [Member]
Schedule of Equity Method Investments [Line Items]
Balance		108,507
Acquisitions		0
Equity income, net		4,830
Contributions	[3]	0
Distributions		(5,189)
Distributions in excess of cumulative earnings	[4]	0
Balance		108,148
Panola [Member]
Schedule of Equity Method Investments [Line Items]
Balance		22,769
Acquisitions		0
Equity income, net		582
Contributions	[3]	0
Distributions		(582)
Distributions in excess of cumulative earnings	[4]	(228)
Balance		22,541
Mi Vida [Member]
Schedule of Equity Method Investments [Line Items]
Balance		64,632
Acquisitions		0
Equity income, net		1,685
Contributions	[3]	0
Distributions		(2,451)
Distributions in excess of cumulative earnings	[4]	0
Balance		63,866
Ranch Westex [Member]
Schedule of Equity Method Investments [Line Items]
Balance		50,901
Acquisitions		0
Equity income, net		2,027
Contributions	[3]	0
Distributions		(3,087)
Distributions in excess of cumulative earnings	[4]	(132)
Balance		49,709
Red Bluff Express [Member]
Schedule of Equity Method Investments [Line Items]
Balance		0
Acquisitions		92,546
Equity income, net		488
Contributions	[3]	7,679
Distributions		(488)
Distributions in excess of cumulative earnings	[4]	(60)
Balance		$ 100,165

[1] Financial information has been recast to include the financial position and results attributable to AMA. See Note 1 and Note 3.

[2] Represents amounts earned or incurred on and subsequent to the date of the acquisition of Partnership assets, as well as amounts earned or incurred by Anadarko on a historical basis related to the Partnership assets prior to the acquisition of such assets.

[3] Includes capitalized interest of $1.5 million related to the construction of the pipeline owned by Cactus II.

[4] Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, are calculated on an individual investment basis.