Transactions with Affiliates (Details) $ in Thousands	1 Months Ended	3 Months Ended
	Apr. 30, 2016 USD ($)	Mar. 31, 2016 USD ($) employee	Mar. 31, 2015 USD ($)	Dec. 31, 2015 USD ($)
Related Party Transaction [Line Items]
Advances to affiliate		$ 1,029,254		$ 64,608
Related party transaction, rate		0.22%
Entity number of employees | employee		0
Expenses, related party		$ 82,900	$ 81,000
Severance Costs		6,300
Cash distributions to parent		175,000	123,000
Cash contributions from parent		112,000	158,000
Affiliated Entity [Member]
Related Party Transaction [Line Items]
Operating revenues, related party		1,200	1,200
Cost of natural gas sales, related party		1,300	2,500
Expenses, related party		(1,100)	$ (1,200)
Williams Partners L.P. [Member]
Related Party Transaction [Line Items]
Advances to affiliate		$ 1,029,300		$ 64,600
Subsequent Event [Member]
Related Party Transaction [Line Items]
Cash distributions to parent	$ 85,000
Cash contributions from parent	$ 110,000