Transactions With Affiliates - Gains Losses Commodity Price Swap Table (details) (Western Gas Partners [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	$ 6,831		$ (6,988)
Sales [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	26,685	[1]	10,204	[1]
Cost Of Sales Member
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	(19,854)	[2]	(17,192)	[2]
Natural Gas Per Thousand Cubic Feet Member | Sales [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	5,380	[1]	9,850	[1]
Natural Gas Liquids [Member] | Sales [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	$ 21,305	[1]	$ 354	[1]

[1] Reported in affiliate natural gas, NGLs and condensate sales in the consolidated statements of income in the period in which the related sale is recorded.

[2] Reported in cost of product in the consolidated statements of income in the period in which the related purchase is recorded.