Transactions With Affiliates - Gains Losses Commodity Price Swap Agreements Table (details) (Western Gas Partners [Member], USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	$ 54,868		$ 38,164		$ 14,215
Sales [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	123,360	[1]	123,458	[1]	103,925	[1]
Sales [Member] | Natural Gas [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	9,494	[1]	21,382	[1]	37,665	[1]
Sales [Member] | Natural Gas Liquids [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	113,866	[1]	102,076	[1]	66,260	[1]
Cost of Sales [Member]
Gains (losses) on commodity price swap
Net gains (losses) on commodity price swap agreements	$ (68,492)	[2]	$ (85,294)	[2]	$ (89,710)	[2]

[1] Reported in affiliate natural gas, natural gas liquids 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.