Transactions with Affiliates (Details) $ in Thousands	1 Months Ended	3 Months Ended		9 Months Ended
	Oct. 31, 2016 USD ($)	Sep. 30, 2016 USD ($) employee	Sep. 30, 2015 USD ($)	Sep. 30, 2016 USD ($) employee	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Advances to affiliate		$ 782,887		$ 782,887		$ 64,608
Related party transaction, rate				0.27%
Entity number of employees | employee		0		0
Expenses, related party		$ 78,400	$ 80,000	$ 234,700	$ 242,600
Severance Costs				6,300
Cash distributions to parent				350,000	374,000
Cash contributions from parent				372,000	491,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Operating revenues, related party		4,800	1,700	8,900	3,600
Cost of natural gas sales, related party		1,800	700	3,300	4,900
Expenses, related party		(1,000)	$ (1,500)	(3,400)	$ (4,200)
Williams Partners L.P. [Member]
Related Party Transaction [Line Items]
Advances to affiliate		$ 782,900		$ 782,900		$ 64,600
Subsequent Event [Member]
Related Party Transaction [Line Items]
Cash distributions to parent	$ 90,000
Cash contributions from parent	$ 130,000