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Equity Investments - Additional Information (Details) - Western Gas Partners, LP [Member] - Fort Union [Member]
$ in Millions
3 Months Ended
Mar. 31, 2016
USD ($)
Schedule of Equity Method Investments [Line Items]  
Equity investment impairment loss $ 3.0
Equity Investments [Member]  
Schedule of Equity Method Investments [Line Items]  
Percentage ownership interest 14.81% [1]
[1] Investments in non-controlled entities over which WES exercises significant influence are accounted for under the equity method. “Equity investment throughput” refers to WES’s share of average throughput for these investments.