Transactions with Affiliates (Details Textual) (USD $)	3 Months Ended		9 Months Ended			9 Months Ended				9 Months Ended		1 Months Ended	9 Months Ended
	Sep. 30, 2012 Employees	Sep. 30, 2011	Sep. 30, 2012 Employees	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Affiliated Entity [Member]	Sep. 30, 2011 Affiliated Entity [Member]	Sep. 30, 2012 Williams Partners L.P. [Member]	Dec. 31, 2011 Williams Partners L.P. [Member]	Sep. 30, 2012 Williams Field Services Company [Member]	Sep. 30, 2011 Williams Field Services Company [Member]	Oct. 30, 2012 Williams Partners Operating LLC [Member]	Sep. 30, 2012 Williams Partners Operating LLC [Member]	Sep. 30, 2011 Williams Partners Operating LLC [Member]	Sep. 30, 2012 Transco Pipeline Services LLC [Member]	Sep. 30, 2011 Transco Pipeline Services LLC [Member]
Related Party Transaction [Line Items]
Advances to affiliates	$ 317,797,000		$ 317,797,000		$ 253,611,000			$ 317,800,000	$ 253,600,000
Related Party Transaction, Rate			0.01%
Total operating revenues	302,957,000	321,694,000	906,600,000	927,901,000		8,600,000	17,900,000
Cost of natural gas sales	15,828,000	36,368,000	36,691,000	89,649,000		3,200,000	6,100,000
Administrative and general	42,443,000	34,900,000	131,225,000	113,527,000		54,900,000	40,200,000
Total operating costs and expenses	231,945,000	232,435,000	678,640,000	664,720,000						(2,700,000)	(3,700,000)
Cash distributions to parent			196,259,000	152,000,000								50,000,000	196,300,000	152,000,000
Cash contributions from parent			117,000,000	100,000,000								33,000,000	117,000,000	100,000,000
Entity Number of Employees	0		0
Labor And Related Expense															$ 155,000,000	$ 142,700,000