Components of Working Capital - Accrued Liabilities Table (details) (USD $)	3 Months Ended
	Mar. 31, 2015		Dec. 31, 2014
Accrued Liabilities [Line Items]
Accrued interest expense	$ 27,995,000		$ 24,741,000
Short-term asset retirement obligations	5,739,000		1,224,000
Short-term remediation and reclamation obligations	475,000		475,000
Income taxes payable	299,000		207,000
Total accrued liabilities	171,786,000		170,864,000	[1]
Accrued Capital Expenditures [Member]
Accrued Liabilities [Line Items]
Other accrued liabilities	94,176,000		128,856,000
Accrued Plant Purchases [Member]
Accrued Liabilities [Line Items]
Other accrued liabilities	37,826,000		14,023,000
Other Accrued Liabilities [Member]
Accrued Liabilities [Line Items]
Other accrued liabilities	5,276,000	[2]	1,338,000	[2]
Western Gas Partners [Member] | Delaware Basin Midstream Limited Liability Company [Member]
Table Text Block Supplement [Abstract]
Post-closing purchase price adjustments	$ 3,500,000

[1] Financial information has been recast to include the financial position and results attributable to the DBJV system. See Note 1 and Note 2.

[2] Includes $3.5 million of post-closing purchase price adjustments at March 31, 2015, related to WES’s acquisition of DBM.