Debt and Financing Arrangements Line of Credit Facility (Details)	Sep. 30, 2019 USD ($)
Line of Credit Facility [Line Items]
Letters of Credit Outstanding, Amount	$ 0
Letter of credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500,000,000
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
Credit Agreement Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	500,000,000
Letters of credit, loans outstanding	0
Commercial paper, outstanding	0
Credit Agreement Member] | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	4,500,000,000
Additional Amount By Which Credit Facility Can Be Increased	500,000,000
Commercial Paper [Member] | Williams Companies Inc [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 4,000,000,000.0