Debt, Financing Arrangements, and Leases (Details) - USD ($)				12 Months Ended
	Apr. 15, 2017	Feb. 02, 2015	Oct. 02, 2009	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Debt issuance costs				$ (2,415,000)	$ (624,000)
Unamortized debt discount				(963,000)	(216,000)
Long-term debt due within one year				249,874,000	184,924,000
Total long-term debt, including current portion				331,748,000	334,236,000
Total long-term debt				331,748,000	334,236,000
Maturities of long-term debt
2018: 6.05% senior unsecured notes				250,000,000
2019				0
2020				0
2021				0
2022				0
Total				250,000,000
Extinguishment of Debt [Line Items]
Retirement of Long-Term Debt	$ 185,000,000
Line of Credit Facility [Line Items]
Lease, initial term			10 years
Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract]
2018				2,761,000
2019				2,787,000
Total				5,548,000
Operating Leases, Rent Expense, Net [Abstract]
Operating lease rent expense, net of sublease revenues				3,500,000	2,700,000	$ 2,700,000
Minimum [Member]
Line of Credit Facility [Line Items]
Lease, renewal term			5 years
Maximum [Member]
Line of Credit Facility [Line Items]
Lease, renewal term			10 years
Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 3,500,000,000
Additional amount by which credit facility can be increased		500,000,000
Line of credit facility, remaining borrowing capacity		$ 500,000,000
Commercial paper				0
Williams Partners L.P. [Member] | Rate addition to federal funds effective rate [Member]
Line of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate		0.50%
Williams Partners L.P. [Member] | Rate addition to London interbank offered rate (LIBOR) [Member]
Line of Credit Facility [Line Items]
Line of credit facility, basis spread on variable rate		1.00%
5.95% senior unsecured notes due 2017 [Member]
Debt Instrument [Line Items]
Long-term debt				$ 0	185,000,000
Interest rate stated percentage				5.95%
6.05% senior unsecured notes due 2018 [Member]
Debt Instrument [Line Items]
Long-term debt				$ 250,000,000	250,000,000
7.125% unsecured debentures due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt				85,000,000	85,000,000
4% Senior Unsecured Notes Due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt				$ 250,000,000	$ 0
Interest rate stated percentage				4.00%
Proceeds from Issuance of Unsecured Debt	$ 250,000,000
$3.5 billion credit facility | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Letters of credit outstanding, amount				$ 0
Line of credit facility, amount outstanding				$ 0
Swing Line Advances [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 150,000,000
Letter of credit [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		1,125,000,000
Commercial paper [Member] | Williams Partners L.P. [Member]
Line of Credit Facility [Line Items]
Line of credit facility, maximum borrowing capacity		$ 3,000,000,000