Debt and Financing Arrangements (Details Textual) (USD $)	Mar. 31, 2013
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 400,000,000
Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,400,000,000
Line of Credit Facility, Amount Outstanding	250,000,000
Williams Partners L.P. [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	1,300,000,000
Letters of Credit Outstanding, Amount	$ 0