Debt and Interest Expense - Interest Expense Table (details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014		Dec. 31, 2013		Dec. 31, 2012
Debt Instrument [Line Items]
Interest expense	$ 76,769	[1]	$ 51,797	[1]	$ 42,060	[1]
Third Parties [Member]
Debt Instrument [Line Items]
Interest expense	76,766		51,797		39,294
Affiliated Entity [Member]
Debt Instrument [Line Items]
Interest expense	3	[2]	0	[2]	2,766	[2]
Anadarko [Member] | Working Capital Facility [Member]
Debt Instrument [Line Items]
Interest expense, related party	3		0		0
Western Gas Partners [Member] | Third Parties [Member]
Debt Instrument [Line Items]
Interest expense on long-term debt	81,495		59,293		41,171
Amortization of debt issuance costs and commitment fees	5,103		4,449		4,319
Capitalized interest	(9,832)		(11,945)		(6,196)
Western Gas Partners [Member] | Affiliated Entity [Member]
Debt Instrument [Line Items]
Interest expense, related party	0	[3]	0	[3]	2,440	[3]
Interest expense on affiliate balances	$ 0	[4]	$ 0	[4]	$ 326	[4]

[1] Includes affiliate (as defined in Note 1) interest expense of zero for each of the years ended December 31, 2014 and 2013, and $2.8 million for the year ended December 31, 2012. See Note 13.

[2] For the year ended December 31, 2014, includes interest expense recognized on the WGP working capital facility (see Note 13). For the year ended December 31, 2012, includes interest expense recognized on the WES note payable to Anadarko (see Note 13) and interest imputed on the reimbursement payable to Anadarko for certain expenditures Anadarko incurred in 2011 related to the construction of the Brasada complex and Lancaster plant. WES repaid the WES note payable to Anadarko in June 2012, and repaid the reimbursement payable to Anadarko associated with the construction of the Brasada complex and Lancaster plant in the fourth quarter of 2012.

[3] In June 2012, the note payable to Anadarko was repaid in full. See Note payable to Anadarko within this Note 13.

[4] Imputed interest expense on the reimbursement payable to Anadarko for certain expenditures Anadarko incurred in 2011 related to the construction of the Brasada complex and Lancaster plant. In the fourth quarter of 2012, WES repaid the reimbursement payable to Anadarko associated with the construction of the Brasada complex and Lancaster plant.