Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		3 Months Ended			6 Months Ended
		Jun. 30, 2015	Jun. 30, 2014	[4]	Jun. 30, 2015		Jun. 30, 2014	[4]
Schedule of Equity Method Investments [Line Items]
Balance	[1]				$ 634,492
Investment earnings (loss), net of amortization	[2],[3]	$ 18,941	$ 13,008		37,161	[5]	$ 22,259	[5]
Contributions					6,770		60,102
Distributions	[5]				(39,034)		(26,793)
Distributions in excess of cumulative earnings	[5]				(8,538)	[6]	$ (9,848)
Balance		630,851			630,851
Western Gas Partners, LP [Member] | Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance					25,933
Investment earnings (loss), net of amortization					3,191
Contributions					0
Distributions					(3,656)
Distributions in excess of cumulative earnings	[6]				0
Balance		25,468			25,468
Western Gas Partners, LP [Member] | White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance					44,315
Investment earnings (loss), net of amortization					7,214
Contributions					4,370
Distributions					(6,923)
Distributions in excess of cumulative earnings	[6]				(2,026)
Balance		46,950			46,950
Western Gas Partners, LP [Member] | Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance					56,336
Investment earnings (loss), net of amortization					1,001
Contributions					0
Distributions					(1,972)
Distributions in excess of cumulative earnings	[6]				(1,863)
Balance		53,502			53,502
Western Gas Partners, LP [Member] | Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance					121,337
Investment earnings (loss), net of amortization					11,377
Contributions					(433)
Distributions					(12,035)
Distributions in excess of cumulative earnings	[6]				(1,025)
Balance		119,221			119,221
Western Gas Partners, LP [Member] | Texas Express Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					16,790
Investment earnings (loss), net of amortization					231
Contributions					0
Distributions					(436)
Distributions in excess of cumulative earnings	[6]				(80)
Balance		16,505			16,505
Western Gas Partners, LP [Member] | Texas Express Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					198,793
Investment earnings (loss), net of amortization					6,818
Contributions					1,430
Distributions					(6,944)
Distributions in excess of cumulative earnings	[6]				(2,798)
Balance		197,299			197,299
Western Gas Partners, LP [Member] | Front Range Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance					170,988
Investment earnings (loss), net of amortization					7,329
Contributions					1,403
Distributions					(7,068)
Distributions in excess of cumulative earnings	[6]				(746)
Balance		$ 171,906			$ 171,906

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

[2] Income earned from equity investments is classified as affiliate. See Note 1.

[3] 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.

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

[5] Income earned on, distributions from and contributions to equity investments are classified as affiliate. See Note 1.

[6] 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.