Transactions with Affiliates (Details Textual) (USD $)	3 Months Ended		6 Months Ended			6 Months Ended				6 Months Ended		1 Months Ended	6 Months Ended
	Jun. 30, 2012 Employees	Jun. 30, 2011	Jun. 30, 2012 Employees	Jun. 30, 2011	Dec. 31, 2011	Jun. 30, 2012 Affiliated Entity [Member]	Jun. 30, 2011 Affiliated Entity [Member]	Jun. 30, 2012 Williams Partners L.P. [Member]	Dec. 31, 2011 Williams Partners L.P. [Member]	Jun. 30, 2012 Williams Field Services Company [Member]	Jun. 30, 2011 Williams Field Services Company [Member]	Jul. 31, 2012 Williams Partners Operating LLC [Member]	Jun. 30, 2012 Williams Partners Operating LLC [Member]	Jun. 30, 2011 Williams Partners Operating LLC [Member]	Jun. 30, 2012 Transco Pipeline Services LLC [Member]	Jun. 30, 2011 Transco Pipeline Services LLC [Member]
Related Party Transaction [Line Items]
Advances to affiliates	$ 285,952,000		$ 285,952,000		$ 253,611,000			$ 286,000,000	$ 253,600,000
Related Party Transaction, Rate			0.01%
Total operating revenues	293,764,000	300,851,000	603,643,000	606,207,000		1,100,000	9,900,000
Cost of natural gas sales	10,717,000	26,239,000	20,863,000	53,281,000		2,400,000	4,500,000
Administrative and general	42,712,000	37,885,000	88,782,000	78,627,000		36,100,000	27,000,000
Total operating costs and expenses	230,274,000	223,730,000	446,695,000	432,285,000						(1,600,000)	(2,100,000)
Cash distributions to parent			136,259,000	101,000,000								60,000,000	136,300,000	101,000,000
Cash contributions from parent			69,000,000	86,000,000								48,000,000	69,000,000	86,000,000
Entity Number of Employees	0		0
Labor And Related Expense															$ 101,900,000	$ 95,200,000