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Debt and Interest Expense - Debt Outstanding Table (Details) - USD ($)
Mar. 31, 2016
Dec. 31, 2015
Debt Instrument [Line Items]    
Total long-term debt principal $ 3,078,000,000 $ 2,720,000,000
Carrying value 3,049,325,000 2,690,651,000 [1]
Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [2] 2,808,729,000 2,492,466,000
WGP RCF [Member] | Revolving Credit Facility [Member]    
Debt Instrument [Line Items]    
Principal 28,000,000 0
Carrying value 28,000,000 0
WGP RCF [Member] | Revolving Credit Facility [Member] | Market Approach Valuation Technique [Member] | Level 2 Inputs [Member]    
Debt Instrument [Line Items]    
Fair value [2] 28,000,000 0
Western Gas Partners, LP [Member] | WES RCF [Member] | Revolving Credit Facility [Member]    
Debt Instrument [Line Items]    
Principal 630,000,000 300,000,000
Carrying value 630,000,000 300,000,000
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 [2] 630,000,000 300,000,000
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 493,962,000 493,711,000
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 [2] 480,315,000 513,645,000
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 668,482,000 668,432,000
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 [2] 597,975,000 595,744,000
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 348,826,000 348,706,000
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 [2] 331,187,000 339,293,000
Western Gas Partners, LP [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]    
Debt Instrument [Line Items]    
Principal 400,000,000 400,000,000
Carrying value 389,744,000 389,707,000
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 [2] 313,752,000 321,499,000
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 490,311,000 490,095,000
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 [2] $ 427,500,000 $ 422,285,000
[1] Financial information has been recast to include the financial position and results attributable to the Springfield system. See Note 1 and Note 2.
[2] Fair value is measured using the market approach and Level 2 inputs.