Description of Business and Basis of Presentation - Equity Investments Table (details) (USD $) In Thousands, unless otherwise specified	3 Months Ended				6 Months Ended
	Jun. 30, 2014		Jun. 30, 2013		Jun. 30, 2014		Jun. 30, 2013
Schedule of Equity Method Investments [Line Items]
Balance					$ 593,400	[1]
Investment earnings (loss), net of amortization	13,008	[2]	3,456	[1],[2]	22,259	[2],[3]	7,424	[1],[2],[3]
Contributions					59,245		156,217	[1]
Capitalized interest					857		7,195
Distributions					(26,793)	[3]	(11,032)	[1],[3]
Distributions in excess of cumulative earnings					(9,848)	[3],[4]	0	[1],[3]
Balance	637,478				637,478
Equity Investments [Member]
Schedule of Equity Method Investments [Line Items]
Contributions					57,603
Western Gas Partners [Member] | Fort Union [Member]
Schedule of Equity Method Investments [Line Items]
Balance					25,172
Investment earnings (loss), net of amortization					3,199
Contributions					0
Capitalized interest					0
Distributions					(3,637)
Distributions in excess of cumulative earnings					0	[4]
Balance	24,734				24,734
Western Gas Partners [Member] | White Cliffs [Member]
Schedule of Equity Method Investments [Line Items]
Balance					35,039
Investment earnings (loss), net of amortization					4,906
Contributions					10,000
Capitalized interest					0
Distributions					(4,616)
Distributions in excess of cumulative earnings					(885)	[4]
Balance	44,444				44,444
Western Gas Partners [Member] | Rendezvous [Member]
Schedule of Equity Method Investments [Line Items]
Balance					60,928
Investment earnings (loss), net of amortization					687
Contributions					0
Capitalized interest					0
Distributions					(1,658)
Distributions in excess of cumulative earnings					(1,395)	[4]
Balance	58,562				58,562
Western Gas Partners [Member] | Mont Belvieu Joint Venture [Member]
Schedule of Equity Method Investments [Line Items]
Balance					122,480
Investment earnings (loss), net of amortization					14,713
Contributions					3,956
Capitalized interest					0
Distributions					(16,510)
Distributions in excess of cumulative earnings					0	[4]
Balance	124,639				124,639
Western Gas Partners [Member] | Texas Express Gathering Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Balance					16,649
Investment earnings (loss), net of amortization					317
Contributions					352
Capitalized interest					0
Distributions					(372)
Distributions in excess of cumulative earnings					(338)	[4]
Balance	16,608				16,608
Western Gas Partners [Member] | Texas Express Pipeline Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Balance					197,731
Investment earnings (loss), net of amortization					(53)
Contributions					5,773
Capitalized interest					0
Distributions					0
Distributions in excess of cumulative earnings					(3,710)	[4]
Balance	199,741				199,741
Western Gas Partners [Member] | Front Range Pipeline Limited Liability Company [Member]
Schedule of Equity Method Investments [Line Items]
Balance					135,401
Investment earnings (loss), net of amortization					(1,510)
Contributions					37,522
Capitalized interest					857
Distributions					0
Distributions in excess of cumulative earnings					(3,520)	[4]
Balance	$ 168,750				$ 168,750

[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.