Debt and Interest Expense - Debt Outstanding Table (details) (USD $)	Mar. 31, 2015		Dec. 31, 2014
Debt Instrument [Line Items]
Total long-term debt principal	$ 2,540,000,000		$ 2,430,000,000
Carrying value	2,532,995,000		2,422,954,000	[1]
Fair value	2,647,557,000	[2]	2,511,253,000	[2]
Anadarko [Member]
Debt Instrument [Line Items]
WGP working capital facility - Anadarko	0		1,150,000	[1]
Anadarko [Member] | Working Capital Facility [Member]
Debt Instrument [Line Items]
Principal	0		1,150,000
WGP working capital facility - Anadarko	0		1,150,000
Fair value	0	[2]	1,150,000	[2]
Western Gas Partners [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Principal	620,000,000		510,000,000
Carrying value	620,000,000		510,000,000
Fair value	620,000,000	[2]	510,000,000	[2]
Western Gas Partners [Member] | Senior Notes [Member] | 5.375% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Principal	500,000,000		500,000,000
Carrying value	495,854,000		495,714,000
Fair value	555,175,000	[2]	549,530,000	[2]
Western Gas Partners [Member] | Senior Notes [Member] | 4.000% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Principal	670,000,000		670,000,000
Carrying value	672,841,000		672,930,000
Fair value	683,554,000	[2]	681,942,000	[2]
Western Gas Partners [Member] | Senior Notes [Member] | 2.600% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Principal	350,000,000		350,000,000
Carrying value	350,443,000		350,474,000
Fair value	355,372,000	[2]	352,162,000	[2]
Western Gas Partners [Member] | Senior Notes [Member] | 5.450% Senior Notes due 2044 [Member]
Debt Instrument [Line Items]
Principal	400,000,000		400,000,000
Carrying value	393,857,000		393,836,000
Fair value	$ 433,456,000	[2]	$ 417,619,000	[2]

[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] Fair value is measured using Level 2 inputs.