Description of Business and Basis of Presentation - Equity Method Investment Table (details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Mar. 31, 2014		Mar. 31, 2013
Schedule of Equity Method Investments [Line Items]
Balance	$ 593,400	[1]
Investment earnings (loss), net of amortization	9,251	[2],[3]	3,968	[1],[2],[3]
Contributions	27,605		64,580	[1]
Distributions	(10,269)	[3]	(5,006)	[1],[3]
Distributions in excess of cumulative earnings	(2,044)	[3]	0	[1],[3]
Balance	613,207
Fort Union [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	25,172
Investment earnings (loss), net of amortization	1,501
Contributions	0
Capitalized interest	0
Distributions	(1,016)
Distributions in excess of cumulative earnings	0	[4]
Balance	25,657
White Cliffs [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	35,039
Investment earnings (loss), net of amortization	2,227
Contributions	2,500
Capitalized interest	0
Distributions	(2,082)
Distributions in excess of cumulative earnings	(581)	[4]
Balance	37,103
Rendezvous [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	60,928
Investment earnings (loss), net of amortization	244
Contributions	0
Capitalized interest	0
Distributions	(729)
Distributions in excess of cumulative earnings	(859)	[4]
Balance	59,584
Mont Belvieu Joint Venture [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	122,480
Investment earnings (loss), net of amortization	7,124
Contributions	(1,919)
Capitalized interest	0
Distributions	(6,200)
Distributions in excess of cumulative earnings	0	[4]
Balance	121,485
Texas Express Gathering Limited Liability Company [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	16,649
Investment earnings (loss), net of amortization	192
Contributions	352
Capitalized interest	0
Distributions	(242)
Distributions in excess of cumulative earnings	(163)	[4]
Balance	16,788
Texas Express Pipeline Limited Liability Company [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	197,731
Investment earnings (loss), net of amortization	(874)
Contributions	187
Capitalized interest	0
Distributions	0
Distributions in excess of cumulative earnings	(541)	[4]
Balance	196,503
Front Range Pipeline Limited Liability Company [Member] | Western Gas Partners [Member]
Schedule of Equity Method Investments [Line Items]
Balance	135,401
Investment earnings (loss), net of amortization	(1,163)
Contributions	20,992
Capitalized interest	857
Distributions	0
Distributions in excess of cumulative earnings	0	[4]
Balance	$ 156,087

[1] Financial information has been recast to include the financial position and results attributable to the TEFR Interests. See Note 1 and Note 2.

[2] Income earned from equity investments is classified as affiliate. See Note 1.

[3] Income earned on, distributions from and contributions to equity investments are classified as affiliate. See Note 1.

[4] Distributions in excess of cumulative earnings, classified as investing cash flows in the consolidated statements of cash flows, is calculated on an individual investment basis.