Debt and Financing Arrangements (Details) - USD ($) $ in Millions	Jul. 31, 2018	Jun. 30, 2018	Mar. 15, 2018
Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 500.0
Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 3,500.0
Commercial paper, outstanding		0.0
Williams Companies Inc [Member] | Subsequent Event [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	$ 4,500.0
$3.5 billion credit facility [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount		0.0
Additional Amount By Which Credit Facility Can Be Increased		500.0
Line of credit facility, amount outstanding		0.0
$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		3,000.0
$3.5 billion credit facility [Member] | Williams Partners L.P. [Member] | Letter of credit [Member]
Line of Credit Facility [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 1,125.0
4%SeniorUnsecuredNotesDue2028
Line of Credit Facility [Line Items]
Additional Interest Rate Accrued For Default Of Registration Rights Agreements First Period			0.25%
Additional Interest Rate Accrued For Default Of Registration Rights Agreements Each Subsequent Period			0.25%
Maximum Additional Interest Rate Accrued For Default Of Registration Rights Agreements All Periods			0.50%