Transactions with Affiliates (Details) (USD $)	3 Months Ended		6 Months Ended					6 Months Ended		1 Months Ended
	Jun. 30, 2014 employee	Jun. 30, 2013	Jun. 30, 2014 employee	Jun. 30, 2013	Dec. 31, 2013	Jun. 30, 2014 Williams Partners L.P. [Member]	Dec. 31, 2013 Williams Partners L.P. [Member]	Jun. 30, 2014 Williams Partners Operating LLC [Member]	Jun. 30, 2013 Williams Partners Operating LLC [Member]	Jul. 31, 2014 Subsequent Event [Member] Williams Partners Operating LLC [Member]
Related Party Transaction [Line Items]
Advances to affiliate	$ 168,257,000		$ 168,257,000		$ 119,168,000	$ 168,300,000	$ 119,200,000
Related party transaction, rate			0.01%
Entity number of employees	0		0
Related party transaction, expenses from transactions with related party	40,600,000	29,000,000	70,900,000	55,400,000
Equity distributions to parent			$ 104,000,000	$ 27,000,000				$ 104,000,000	$ 27,000,000.0	$ 37,000,000