Debt and Interest Expense - Debt Activity Table (details) $ in Thousands	3 Months Ended
Mar. 31, 2015 USD ($)
Debt Instrument [Line Items]
Beginning balance	$ 2,424,104
Ending balance	2,532,995
Anadarko [Member] \| Working Capital Facility [Member]
Debt Instrument [Line Items]
Repayment	(1,150)
Western Gas Partners [Member]
Debt Instrument [Line Items]
Other	41
Western Gas Partners [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Borrowings	140,000
Repayment	$ (30,000)

Amount of noncash expense included in interest expense to amortize debt discount and premium associated with the related debt instruments. Excludes amortization of financing costs. Alternate captions include noncash interest expense.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=56944662&loc=d3e3602-108585

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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-URI http://asc.fasb.org/extlink&oid=6451184&loc=d3e28541-108399

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.8)
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Glossary Financing Activities
-URI http://asc.fasb.org/extlink&oid=6513228

Reference 2: http://www.xbrl.org/2003/role/presentationRef
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