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Debt and Interest Expense - Debt Outstanding Table (Details) - USD ($)
Sep. 30, 2017
Dec. 31, 2016
Debt Instrument [Line Items]    
Total long-term debt principal $ 3,398,000,000 $ 3,148,000,000
Carrying value 3,371,886,000 3,119,461,000
Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 3,522,945,000 3,224,199,000
WGP RCF [Member] | Revolving Credit Facility [Member]    
Debt Instrument [Line Items]    
Principal 28,000,000 28,000,000
Carrying value 28,000,000 28,000,000
WGP RCF [Member] | Revolving Credit Facility [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 28,000,000 28,000,000
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member]    
Debt Instrument [Line Items]    
Principal 250,000,000 0
Carrying value 250,000,000 0
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 250,000,000 0
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]    
Debt Instrument [Line Items]    
Principal 500,000,000 500,000,000
Carrying value 495,541,000 494,734,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 536,712,000 536,252,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]    
Debt Instrument [Line Items]    
Principal 670,000,000 670,000,000
Carrying value 668,795,000 668,634,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 693,789,000 681,723,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]    
Debt Instrument [Line Items]    
Principal 350,000,000 350,000,000
Carrying value 349,558,000 349,188,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 351,770,000 351,531,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]    
Debt Instrument [Line Items]    
Principal 600,000,000 600,000,000
Carrying value 593,206,000 593,132,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 634,283,000 615,753,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member]    
Debt Instrument [Line Items]    
Principal 500,000,000 500,000,000
Carrying value 491,653,000 490,971,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 3.950% Senior Notes due 2025 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] 503,322,000 492,499,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member]    
Debt Instrument [Line Items]    
Principal 500,000,000 500,000,000
Carrying value 495,133,000 494,802,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 4.650% Senior Notes due 2026 [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [1] $ 525,069,000 $ 518,441,000
[1] Fair value is measured using the market approach and Level 2 inputs.