Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012
Cash flows from operating activities
Net income	$ 193,926		$ 126,293	[1]
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation, amortization and impairments	106,551		83,263	[1]
Non-cash equity-based compensation expense	2,783		2,769	[1]
Deferred income taxes	1,207		(11,275)	[1]
Debt-related amortization and other items, net	1,756		1,728	[1]
Changes in assets and liabilities:
(Increase) decrease in accounts receivable, net	(27,539)		47,272	[1]
Increase (decrease) in accounts and natural gas imbalance payables and accrued liabilities, net	6,700		29,272	[1]
Change in other items, net	687		2,234	[1]
Net cash provided by operating activities	286,071		281,556	[1]
Cash flows from investing activities
Capital expenditures	(469,678)		(403,949)	[1]
Investments in equity affiliates	(45,126)		(147)	[1]
Other	(1,524)		0	[1]
Net cash used in investing activities	(1,226,404)		(1,009,296)	[1]
Cash flows from financing activities
Borrowings, net of debt issuance costs	842,566		885,291	[1]
Repayments of debt	(495,000)		(549,000)	[1]
Increase (decrease) in outstanding checks	(3,335)		2,534	[1]
Offering expenses from the issuance of WGP common units	(2,367)		0
Distributions to WGP unitholders	(90,211)		0	[1]
Distributions to WES common unitholders	(94,117)		(71,890)	[1]
Net contributions from Anadarko	4,508		57,190	[1]
Net cash provided by financing activities	574,860		548,675	[1]
Net increase (decrease) in cash and cash equivalents	(365,473)		(179,065)	[1]
Cash and cash equivalents at beginning of period	422,556	[1]	226,559	[1]
Cash and cash equivalents at end of period	57,083		47,494	[1]
Supplemental disclosures
Net distributions to Anadarko of other assets	4,080		10,790	[1]
Interest paid, net of capitalized interest	34,974		16,460	[1]
Taxes paid	0		495	[1]
Western Gas Partners [Member]
Cash flows from financing activities
Proceeds from issuance of WES common units, net of offering expenses	418,570		211,965	[1]
Affiliated Entity [Member]
Cash flows from investing activities
Acquisitions	(469,884)		(605,960)	[1]
Proceeds from sale of assets to affiliates	82		760	[1]
Third Parties [Member]
Cash flows from investing activities
Acquisitions	(240,274)		0	[1]
Chipeta Processing Limited Liability Company [Member]
Cash flows from financing activities
Contributions received from Chipeta noncontrolling interest owners (including Anadarko)	2,247		26,888	[1]
Distributions to Chipeta noncontrolling interest owners (including Anadarko)	$ (8,001)		$ (14,303)	[1]

[1] Financial information has been recast to include the financial position and results attributable to the Non-Operated Marcellus Interest. See Note 2.