Transactions With Affiliates - Equipment Purchase and Sale Table (details) (USD $) In Thousands, unless otherwise specified	9 Months Ended						3 Months Ended				9 Months Ended
	Sep. 30, 2013		Dec. 31, 2012		Sep. 30, 2013 Affiliated Entity [Member]	Dec. 31, 2012 Affiliated Entity [Member]	Sep. 30, 2013 Affiliated Entity [Member] Purchases [Member] Western Gas Partners [Member]		Sep. 30, 2012 Affiliated Entity [Member] Purchases [Member] Western Gas Partners [Member]		Sep. 30, 2013 Affiliated Entity [Member] Sales [Member] Western Gas Partners [Member]		Sep. 30, 2012 Affiliated Entity [Member] Sales [Member] Western Gas Partners [Member]
Related Party Transaction [Line Items]
Consideration given for equipment							$ 6,167	[1]	$ 18,946	[1]
Consideration received for equipment											82	[1]	760	[1]
Net carrying value							2,039		6,765		34		392
Partners' capital adjustment	265						4,128		12,181		48		368
Table Text Block Supplement [Abstract]
Accounts payable	$ 19,131	[2]	$ 25,154	[2],[3]	$ 2,800	$ 2,500	$ 1,800

[1] Includes a payable of $1.8 million for pipe and equipment purchased in September 2013.

[2] Accounts and natural gas imbalance payables includes amounts payable to affiliates of $2.8 million and $2.5 million as of September 30, 2013, and December 31, 2012, respectively.

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