Equity Investments - Equity Investments Table (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2016		Dec. 31, 2015		Dec. 31, 2014
Schedule of Equity Method Investments [Line Items]
Balance		$ 618,887		$ 634,492
Investment earnings (loss), net of amortization	[1]	78,717		71,251		$ 57,836
Contributions		27		11,442		64,278
Distributions		(82,185)		(82,054)		(62,967)
Distributions in excess of cumulative earnings		(21,238)	[2]	(16,244)	[2]	(18,055)
Balance		594,208		618,887		634,492
Western Gas Partners, LP [Member] | Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[3]	17,122		25,933
Investment earnings (loss), net of amortization	[3]	608		(3,200)
Contributions	[3]	0		0
Distributions	[3]	(1,543)		(5,611)
Distributions in excess of cumulative earnings	[2],[3]	(3,354)		0
Balance	[3]	$ 12,833		17,122		25,933
Equity investment ownership		14.81%
Approval percentage		65.00%
Western Gas Partners, LP [Member] | White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[4]	$ 50,439		44,315
Investment earnings (loss), net of amortization	[4]	13,858		14,770
Contributions	[4]	441		8,512
Distributions	[4]	(13,277)		(14,188)
Distributions in excess of cumulative earnings	[2],[4]	(4,142)		(2,970)
Balance	[4]	$ 47,319		50,439		44,315
Equity investment ownership		10.00%
Approval percentage		75.00%
Western Gas Partners, LP [Member] | Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[5]	$ 50,913		56,336
Investment earnings (loss), net of amortization	[5]	1,931		2,292
Contributions	[5]	0		0
Distributions	[5]	(3,873)		(4,233)
Distributions in excess of cumulative earnings	[2],[5]	(2,232)		(3,482)
Balance	[5]	$ 46,739		50,913		56,336
Equity investment ownership		22.00%
Approval percentage		100.00%
Western Gas Partners, LP [Member] | Mont Belvieu JV [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[6]	$ 117,089		121,337
Investment earnings (loss), net of amortization	[6]	26,204		23,570
Contributions	[6]	0		(432)
Distributions	[6]	(26,243)		(24,248)
Distributions in excess of cumulative earnings	[2],[6]	(4,245)		(3,138)
Balance	[6]	$ 112,805		117,089		121,337
Equity investment ownership		25.00%
Approval percentage		50.00%
Western Gas Partners, LP [Member] | Mont Belvieu JV [Member] | Fractionation Train [Member]
Schedule of Equity Method Investments [Line Items]
Assets, number of units		2
Western Gas Partners, LP [Member] | Texas Express Gathering LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[7]	$ 16,283		16,790
Investment earnings (loss), net of amortization	[7]	708		586
Contributions	[7]	166		0
Distributions	[7]	(730)		(803)
Distributions in excess of cumulative earnings	[2],[7]	(581)		(290)
Balance	[7]	$ 15,846		16,283		16,790
Equity investment ownership		20.00%
Approval percentage		50.00%
Western Gas Partners, LP [Member] | Texas Express Gathering LLC [Member] | Natural Gas Liquids Gathering System [Member]
Schedule of Equity Method Investments [Line Items]
Assets, number of units		2
Western Gas Partners, LP [Member] | Texas Express Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[8]	$ 194,803		198,793
Investment earnings (loss), net of amortization	[8]	16,683		16,088
Contributions	[8]	(580)		1,880
Distributions	[8]	(16,934)		(16,340)
Distributions in excess of cumulative earnings	[2],[8]	(4,778)		(5,618)
Balance	[8]	$ 189,194		194,803		198,793
Equity investment ownership		20.00%
Approval percentage		50.00%
Western Gas Partners, LP [Member] | Front Range Pipeline LLC [Member]
Schedule of Equity Method Investments [Line Items]
Balance	[9]	$ 172,238		170,988
Investment earnings (loss), net of amortization	[9]	18,725		17,145
Contributions	[9]	0		1,482
Distributions	[9]	(19,585)		(16,631)
Distributions in excess of cumulative earnings	[2],[9]	(1,906)		(746)
Balance	[9]	$ 169,472		$ 172,238		$ 170,988
Equity investment ownership		33.33%
Approval percentage		50.00%

[1] 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.

[2] 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.

[3] WES has a 14.81% interest in Fort Union, a joint venture that owns a gathering pipeline and treating facilities in the Powder River Basin. Anadarko is the construction manager and physical operator of the Fort Union facilities. Certain business decisions, including, but not limited to, decisions with respect to significant expenditures or contractual commitments, annual budgets, material financings, dispositions of assets or amending the owners’ firm gathering agreements, require 65% or unanimous approval of the owners.

[4] WES has a 10% interest in White Cliffs, a limited liability company that owns a crude oil pipeline that originates in Platteville, Colorado and terminates in Cushing, Oklahoma. The third-party majority owner is the manager of the White Cliffs operations. Certain business decisions, including, but not limited to, approval of annual budgets and decisions with respect to significant expenditures, contractual commitments, acquisitions, material financings, dispositions of assets or admitting new members, require more than 75% approval of the members.

[5] WES has a 22% interest in Rendezvous, a limited liability company that operates gas gathering facilities in Southwestern Wyoming. Certain business decisions, including, but not limited to, decisions with respect to significant expenditures or contractual commitments, annual budgets, material financings, dispositions of assets or amending the members’ gas servicing agreements, require unanimous approval of the members.

[6] WES has a 25% interest in the Mont Belvieu JV, an entity formed to design, construct, and own two fractionation trains located in Mont Belvieu, Texas. A third party is the operator of the Mont Belvieu JV fractionation trains. Certain business decisions, including, but not limited to, decisions with respect to the execution of contracts, settlements, disposition of assets, or the creation, appointment, or removal of officer positions require 50% or unanimous approval of the owners.

[7] WES has a 20% interest in TEG, an entity that consists of two NGL gathering systems that link natural gas processing plants to TEP. Enbridge Midcoast Energy, LP (“Enbridge”) is the operator of the two gathering systems. Certain business decisions, including, but not limited to, decisions with respect to the execution of contracts, settlements, disposition of assets, or the delegation, creation, appointment, or removal of officer positions require more than 50% approval of the members.

[8] WES has a 20% interest in TEP, which consists of an NGL pipeline that originates in Skellytown, Texas and extends to Mont Belvieu, Texas. Enterprise Products Operating LLC (“Enterprise”) is the operator of TEP. Certain business decisions, including, but not limited to, decisions with respect to the execution of contracts, settlements, disposition of assets, or the creation, appointment, or removal of officer positions require more than 50% approval of the members.

[9] WES has a 33.33% interest in the FRP, an NGL pipeline that extends from Weld County, Colorado to Skellytown, Texas. Enterprise is the operator of FRP. Certain business decisions, including, but not limited to, decisions with respect to the execution of contracts, settlements, disposition of assets, or the creation, appointment, or removal of officer positions require more than 50% approval of the members.