Debt and Financing Arrangements Line of Credit Facility (Details) - USD ($)	Dec. 31, 2020	Jul. 13, 2018
Swing Line Advances [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 200,000,000
$4.5 billion credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		500,000,000
Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		500,000,000
Williams Companies Inc [Member] | Commercial paper [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		4,000,000,000.0
Commercial paper, amount outstanding	$ 0
Williams Companies Inc [Member] | $4.5 billion credit facility [Member]
Line of Credit Facility [Line Items]
Line of credit facility, amount outstanding	0
Line of credit facility, maximum borrowing capacity		4,500,000,000
Additional amount by which credit facility can be increased		500,000,000
Letters of credit outstanding, amount	$ 0
Williams Companies Inc [Member] | Letter of Credit [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 1,000,000,000.0