Transactions With Affiliates - Additional Information (details) (USD $)					3 Months Ended	1 Months Ended			1 Months Ended	3 Months Ended											3 Months Ended
	Mar. 31, 2013		Dec. 31, 2012		Mar. 31, 2013 Western Gas Partners [Member]	May 31, 2008 Note Receivable From Anadarko [Member] Western Gas Partners [Member]	Mar. 31, 2013 Note Receivable From Anadarko [Member] Western Gas Partners [Member]	Dec. 31, 2012 Note Receivable From Anadarko [Member] Western Gas Partners [Member]	Dec. 31, 2008 Note Payable To Anadarko [Member] Western Gas Partners [Member]	Mar. 31, 2013 Gathering Transportation And Treating [Member] Western Gas Partners [Member]	Mar. 31, 2012 Gathering Transportation And Treating [Member] Western Gas Partners [Member]	Mar. 31, 2013 Processing [Member] Western Gas Partners [Member]	Mar. 31, 2012 Processing [Member] Western Gas Partners [Member]	Mar. 31, 2013 Long Term Incentive Plan [Member]	Mar. 31, 2013 Long Term Incentive Plan [Member] Western Gas Partners [Member]	Mar. 31, 2012 Long Term Incentive Plan [Member] Western Gas Partners [Member]	Mar. 31, 2013 Anadarko Incentive Plans [Member] Western Gas Partners [Member]	Mar. 31, 2012 Anadarko Incentive Plans [Member] Western Gas Partners [Member]	Mar. 31, 2012 Incentive Plan [Member] Western Gas Partners [Member]	Mar. 31, 2012 Anadarko [Member] Brasada And Lancaster Agreement [Member] Western Gas Partners [Member]	Mar. 31, 2013 Director [Member] Long Term Incentive Plan [Member]	Mar. 31, 2013 Director [Member] Long Term Incentive Plan [Member] Western Gas Partners [Member]
Related Party Transaction Line Items
Note receivable - Anadarko	$ 260,000,000		$ 260,000,000	[1]		$ 260,000,000
Term of instrument or obligation					1 year	30 years			5 years
Fixed annual rate for note receivable bearing interest						6.50%
The fair value of the note receivable							326,000,000	334,800,000
Principal	1,555,000,000		1,170,000,000						175,000,000
Fixed interest rate									4.00%
Cost reimbursement payable	147,636,000	[2]	148,600,000	[1],[2]																18,900,000
Affiliate throughput percent										60.00%	66.00%	55.00%	57.00%
Equity based compensation expense														$ 53,000	$ 100,000	$ 100,000	$ 700,000	$ 800,000	$ 3,300,000
Phantom units vesting term															3 years						1 year	1 year
UVR, UAR and DER Valuation																			$ 718.00

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

[2] Accrued liabilities include amounts payable to affiliates of $0.1 million as of March 31, 2013 and December 31, 2012. See Note 5.