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Transactions with Affiliates - Additional Information (Details) - USD ($)
1 Months Ended 3 Months Ended 9 Months Ended
May 31, 2008
Sep. 30, 2018
Sep. 30, 2017
Sep. 30, 2018
Sep. 30, 2017
Dec. 31, 2017
Related Party Transaction [Line Items]            
Note receivable - Anadarko   $ 260,000,000   $ 260,000,000   $ 260,000,000
Above-market component of swap agreements with Anadarko [1]       40,722,000    
Contributions of equity-based compensation to WES by Anadarko       $ 4,306,000    
Western Gas Equity Partners Long Term Incentive Plan [Member]            
Related Party Transaction [Line Items]            
Units vesting period       3 years    
Equity-based compensation expense   62,000 $ 63,000 $ 200,000 $ 200,000  
Commodity Price Swap Agreement [Member]            
Related Party Transaction [Line Items]            
Net gains (losses) on commodity price swap agreements   (3,737,000)   (6,351,000)    
Affiliates [Member] | Commodity Price Swap Agreement [Member]            
Related Party Transaction [Line Items]            
Net gains (losses) on commodity price swap agreements   (3,737,000) (1,000,000) $ (6,351,000) (600,000)  
Independent Director [Member] | Western Gas Equity Partners Long Term Incentive Plan [Member]            
Related Party Transaction [Line Items]            
Units vesting period       1 year    
Western Gas Partners, LP [Member] | Anadarko Incentive Plan [Member]            
Related Party Transaction [Line Items]            
Equity-based compensation expense   1,400,000 1,200,000 $ 5,200,000 3,200,000  
Contributions of equity-based compensation to WES by Anadarko       $ 4,300,000    
Western Gas Partners, LP [Member] | Western Gas Partners Long Term Incentive Plan [Member]            
Related Party Transaction [Line Items]            
Units vesting period       3 years    
Equity-based compensation expense   $ 100,000 $ 100,000 $ 300,000 $ 300,000  
Western Gas Partners, LP [Member] | Natural Gas [Member] | Gathering, Treating, Transportation and Disposal [Member]            
Related Party Transaction [Line Items]            
Affiliate throughput percent   41.00% 33.00% 37.00% 34.00%  
Western Gas Partners, LP [Member] | Natural Gas [Member] | Processing [Member]            
Related Party Transaction [Line Items]            
Affiliate throughput percent   35.00% 39.00% 35.00% 42.00%  
Western Gas Partners, LP [Member] | Crude Oil, NGL and Produced Water [Member] | Gathering, Treating, Transportation and Disposal [Member]            
Related Party Transaction [Line Items]            
Affiliate throughput percent   77.00% 54.00% 71.00% 50.00%  
Western Gas Partners, LP [Member] | Affiliates [Member]            
Related Party Transaction [Line Items]            
Note receivable - Anadarko $ 260,000,000 $ 260,000,000   $ 260,000,000    
Note receivable, due date May 14, 2038          
Fixed annual rate for note receivable bearing interest 6.50%          
Western Gas Partners, LP [Member] | Affiliates [Member] | Level 2 Inputs [Member] | Valuation, Market Approach [Member]            
Related Party Transaction [Line Items]            
Fair value of the note receivable   $ 300,900,000   $ 300,900,000   $ 325,200,000
Western Gas Partners, LP [Member] | Independent Director [Member] | Western Gas Partners Long Term Incentive Plan [Member]            
Related Party Transaction [Line Items]            
Units vesting period       1 year    
[1] See Note 6.