Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2016	Jun. 30, 2015	[3]	Jun. 30, 2016		Jun. 30, 2015	[3]
Schedule of Equity Method Investments [Line Items]
Balance	[1]				$ 618,887
Investment earnings (loss), net of amortization	[2]	$ 19,693	$ 18,941		36,507		$ 37,161
Contributions					(139)		6,770
Distributions					(38,519)		(39,034)
Distributions in excess of cumulative earnings					(10,611)	[4]	$ (8,538)
Balance		606,125			606,125
Western Gas Partners, LP [Member] | Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance					17,122
Investment earnings (loss), net of amortization					(1,360)
Contributions					0
Distributions					0
Distributions in excess of cumulative earnings	[4]				(3,354)
Balance		12,408			12,408
Western Gas Partners, LP [Member] | White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance					50,439
Investment earnings (loss), net of amortization					7,164
Contributions					441
Distributions					(6,873)
Distributions in excess of cumulative earnings	[4]				(2,100)
Balance		49,071			49,071
Western Gas Partners, LP [Member] | Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance					50,913
Investment earnings (loss), net of amortization					949
Contributions					0
Distributions					(1,364)
Distributions in excess of cumulative earnings	[4]				(1,541)
Balance		48,957			48,957
Western Gas Partners, LP [Member] | Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance					117,089
Investment earnings (loss), net of amortization					12,686
Contributions					0
Distributions					(12,303)
Distributions in excess of cumulative earnings	[4]				(172)
Balance		117,300			117,300
Western Gas Partners, LP [Member] | Texas Express Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					16,283
Investment earnings (loss), net of amortization					343
Contributions					0
Distributions					(354)
Distributions in excess of cumulative earnings	[4]				(188)
Balance		16,084			16,084
Western Gas Partners, LP [Member] | Texas Express Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					194,803
Investment earnings (loss), net of amortization					7,766
Contributions					(580)
Distributions					(7,892)
Distributions in excess of cumulative earnings	[4]				(2,918)
Balance		191,179			191,179
Western Gas Partners, LP [Member] | Front Range Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					172,238
Investment earnings (loss), net of amortization					8,959
Contributions					0
Distributions					(9,733)
Distributions in excess of cumulative earnings	[4]				(338)
Balance		$ 171,126			$ 171,126

[1] Financial information has been recast to include the financial position and results attributable to the Springfield interest. See Note 1 and Note 2.

[2] Represents amounts earned or incurred on and subsequent to the date of acquisition of WES assets, as well as amounts earned or incurred by Anadarko on a historical basis related to WES assets prior to the acquisition of such assets by WES, recognized under gathering, treating or processing agreements, and purchase and sale agreements.

[3] Financial information has been recast to include the financial position and results attributable to the Springfield interest. See Note 1 and Note 2.

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