Transactions with Major Customers and Affiliates (Details Textual) (USD $)	12 Months Ended
	Dec. 31, 2012 Employees	Dec. 31, 2011	Dec. 31, 2010
Related Party Transaction [Line Items]
Advances to affiliate	$ 29,322,000	$ 52,024,000
Related Party Transaction, Rate	0.01%
General and administrative	68,473,000	55,735,000	54,067,000
Entity Number of Employees	0
Operating Revenues	437,835,000	434,484,000	421,817,000
Cash distributions	137,500,000	127,000,000	191,450,000
Capital contributions from parent	8,630,000	5,100,000	19,000,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
General and administrative	44,000,000	35,400,000	34,100,000
Operating Revenues		24,700,000	6,800,000
Williams Partners L.P. [Member]
Related Party Transaction [Line Items]
Advances to affiliate	29,300,000	52,000,000
Cash distributions	137,500,000	127,000,000	191,500,000
Capital contributions from parent	8,600,000	5,100,000	19,000,000
Williams Companies Inc. [Member]
Related Party Transaction [Line Items]
Labor and Related Expense	$ 69,000,000	$ 62,600,000	$ 60,600,000