Debt and Interest Expense - Western Gas Partners, LP Additional Information (Detail) (Revolving Credit Facility [Member], USD $)	3 Months Ended
	Mar. 31, 2013
Line of Credit Facility [Line Items]
Line of credit, maximum capacity	$ 5,000,000,000
Western Gas Partners Limited Partnership [Member]
Line of Credit Facility [Line Items]
Line of credit, maximum capacity	800,000,000
Line of credit, expiration date	Mar. 24, 2016
Line of credit, outstanding borrowings	385,000,000
Line of credit, interest rate	1.70%
Line of credit, available borrowing capacity	402,000,000
Outstanding letters of credit	$ 13,000,000