Acquisitions and Divestitures - Impact to Historical Consolidated Statements of Operations Table (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2019	Mar. 31, 2018
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other		$ 671,883	$ 501,054	[1]
Equity income, net – affiliates	[2]	57,992	30,229	[1]
Net income (loss)		211,979	181,010	[1]
Anadarko Midstream Assets [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			51,664
Equity income, net – affiliates			9,805
Net income (loss)			30,522
Anadarko Midstream Assets [Member] | Eliminations [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			(7,412)
Equity income, net – affiliates			0
Net income (loss)			0
Historical financial data [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other	[3]		456,802
Equity income, net – affiliates	[3]		20,424
Net income (loss)	[3]		150,488
WES Operating [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other		671,883	501,054	[1]
Equity income, net – affiliates		57,992	30,229	[1]
Net income (loss)		$ 214,450	182,870	[1]
WES Operating [Member] | Anadarko Midstream Assets [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			51,664
Equity income, net – affiliates			9,805
Net income (loss)			30,522
WES Operating [Member] | Anadarko Midstream Assets [Member] | Eliminations [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other			(7,412)
Equity income, net – affiliates			0
Net income (loss)			0
WES Operating [Member] | Historical financial data [Member]
Error Corrections and Prior Period Adjustments Restatement [Line Items]
Revenues and other	[3]		456,802
Equity income, net – affiliates	[3]		20,424
Net income (loss)	[3]		$ 152,348

[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] See Adjustments to previously issued financial statements within Note 1.