Significant Accounting Policy (Tables)

12 Months Ended

Dec. 31, 2012

Policy Text Block [Abstract]

Schedule Of Property Plant And Equipment Useful Life [Table Text Block]

	Useful Lives
Transmission assets	20-30 years
Gathering systems	15-20 years
Gas processing plants	20 years
Other property and equipment	3-15 years

Schedule of Finite-Lived Intangible Assets [Table Text Block]

		Gross Carrying		Accumulated		Net Carrying
		Amount		Amortization		Amount
2012
Customer relationships		$	292,658	$	(130,458)	$	162,200
Dedicated and non-dedicated acreage			395,652		(132,847)		262,805
	Total	$	688,310	$	(263,305)	$	425,005
2011
Customer relationships		$	255,058	$	(101,762)	$	153,296
Dedicated and non-dedicated acreage			395,652		(97,486)		298,166
	Total	$	650,710	$	(199,248)	$	451,462

Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block]

2013	$	48,156
2014		45,129
2015		43,319
2016		43,429
2017		42,375
Thereafter		202,597
Total	$	425,005

Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]

		Years Ended December 31,
		2012		2011		2010
Cost of share-based compensation charged to general and administrative
	expense	$	8,240	$	6,405	$	8,246
Cost of share-based compensation charged to operating expense			1,243		1,151		1,323
Total amount charged to income		$	9,483	$	7,556	$	9,569
Interest of non-controlling partners in share-based compensation		$	3,813	$	3,052	$	3,900
Amount of related income tax benefit recognized in income		$	2,102	$	1,670	$	2,038