Debt and Financing Arrangement (Details) - USD ($)	Sep. 30, 2015	Feb. 02, 2015
Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 3,500,000,000
Commercial paper, outstanding	$ 1,530,000,000
$3.5 billion credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	500,000,000
$3.5 billion credit facility [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount	0
Line of credit facility, amount outstanding	500,000,000
$3.5 billion credit facility [Member] | Williams Partners L.P. [Member] | Commercial paper [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	3,000,000,000
$3.5 billion credit facility [Member] | Letter of credit | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity	$ 1,125,000,000