Transactions with Major Customers and Affiliates (Details Textual) (USD $)	1 Months Ended	12 Months Ended
	Jan. 31, 2013	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Advances to affiliate		$ 312,165,000	$ 253,611,000
Related Party Transaction, Rate		0.01%
Total operating revenues		1,234,101,000	1,242,514,000	1,181,995,000
Cost of natural gas sales		65,120,000	108,359,000	99,346,000
Entity Number of Employees		0
Administrative and general		174,610,000	148,113,000	148,589,000
Total operating costs and expenses		904,040,000	887,963,000	842,528,000
Cash distributions		246,259,000	219,000,000	333,791,000
Cash contributions from parent		150,000,000	115,000,000	75,000,000
Non-cash contributions from parent		1,524,000	0	0
Non-cash return of capital		0	(546,000)	0
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Total operating revenues		17,000,000	18,500,000	23,400,000
Cost of natural gas sales		3,900,000	8,800,000	4,800,000
Administrative and general		75,600,000	52,600,000	54,700,000
Williams Partners L.P. [Member]
Related Party Transaction [Line Items]
Advances to affiliate		312,200,000	253,600,000
Williams Field Services Company [Member]
Related Party Transaction [Line Items]
Total operating costs and expenses		(4,500,000)	(6,400,000)	(8,700,000)
ContributionsInAidOfConstruction		2,300,000	4,500,000	13,500,000
Williams Partners Operating LLC [Member]
Related Party Transaction [Line Items]
Cash distributions	65,000,000	246,000,000	219,000,000	334,000,000
Cash contributions from parent	55,000,000	150,000,000	115,000,000	75,000,000
Non-cash contributions from parent		1,500,000
Non-cash return of capital			500,000
The Williams Companies, Inc.[Member]
Related Party Transaction [Line Items]
Labor And Related Expense		206,100,000	191,100,000	170,700,000
Williams Gas Processing - Gulf Coast Company, L.P. [Member]
Related Party Transaction [Line Items]
Reimbursement Revenue		$ 3,100,000