Transactions with Affiliates (Details Textual) (USD $)	6 Months Ended					3 Months Ended		6 Months Ended		1 Months Ended	6 Months Ended
	Jun. 30, 2013 Employees	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Williams Partners L.P. [Member]	Dec. 31, 2012 Williams Partners L.P. [Member]	Jun. 30, 2013 The Williams Companies, Inc.[Member]	Jun. 30, 2012 The Williams Companies, Inc.[Member]	Jun. 30, 2013 The Williams Companies, Inc.[Member]	Jun. 30, 2012 The Williams Companies, Inc.[Member]	Jul. 31, 2013 Williams Partners Operating LLC [Member]	Jun. 30, 2013 Williams Partners Operating LLC [Member]	Jun. 30, 2012 Williams Partners Operating LLC [Member]
Related Party Transaction [Line Items]
Advances to affiliate	$ 112,195,000		$ 29,322,000	$ 112,200,000	$ 29,300,000
Related Party Transaction, Rate	0.01%
Entity Number of Employees	0
RelatedPartyTransactionExpensesFromTransactionsWithRelatedParty						27,900,000	28,800,000	54,300,000	55,000,000
Distributions paid	27,000,000	73,000,000								35,000,000	27,000,000	73,000,000
Capital contributions from parent	$ 0	$ 2,330,000								$ 1,900,000	$ 0	$ 2,300,000