Debt and Financing Arrangements (Details Textual) (USD $)	Jun. 30, 2012
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 400,000,000
Letters of Credit Outstanding, Amount	0
$2 billion unsecured credit facility [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	2,000,000,000
Line of Credit Facility, Amount Outstanding	345,000,000
$2 billion unsecured credit facility [Member] | Letter Of Credit Capacity [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 1,300,000,000