Acquisitions - Pro Forma Condensed Financial Information Table (details) (Delaware Basin Midstream Limited Liability Company [Member], USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013
Delaware Basin Midstream Limited Liability Company [Member]
Business Acquisition [Line Items]
Revenues	$ 1,397,030	$ 1,107,030
Net income	329,241	235,817
Net income attributable to Western Gas Equity Partners, LP	$ 163,773	$ 129,984
Net income per common unit - basic and diluted	$ 0.75	$ 0.57