Debt and Financing Arrangements Long-term Debt Instruments (Details) - USD ($) $ in Thousands	Apr. 15, 2016	Mar. 31, 2016	Jan. 22, 2016	Dec. 31, 2015
Debt Instrument [Line Items]
Long-term debt, face amount			$ 1,000,000
Long-term debt due within one year		$ 199,987		$ 0
6.4% due 2016 [Member]
Debt Instrument [Line Items]
Long-term debt due within one year		$ 200,000
Long-term debt, interest rate		6.40%
6.4% due 2016 [Member] | Subsequent Event [Member]
Debt Instrument [Line Items]
Long-term debt retired	$ 200,000
7.85% Senior Unsecured Notes Due 2026 [Member]
Debt Instrument [Line Items]
Long-term debt, interest rate			7.85%
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%
Williams Partners L.P. [Member]
Debt Instrument [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity		$ 3,500,000