Debt And Related Expenses (Schedule Of Debt Instruments and Balances) (Parenthetical) (Details) - USD ($) $ in Millions		6 Months Ended
		Jun. 30, 2018	Dec. 31, 2017
Debt Instrument [Line Items]
Short-term debt	[1]	$ 277	$ 115
8.25% Due July 1, 2018 [Member]
Debt Instrument [Line Items]
Short-term debt		$ 20	$ 20
Debt interest rate, stated percentage		8.25%	8.25%
Debt, maturity date		Jul. 01, 2018
2.25% Due December 15, 2018 [Member]
Debt Instrument [Line Items]
Short-term debt		$ 95	$ 95
Debt interest rate, stated percentage		2.25%	2.25%
Debt, maturity date		Dec. 15, 2018
6.30% Due January 15, 2019 [Member]
Debt Instrument [Line Items]
Short-term debt		$ 162
Debt interest rate, stated percentage		6.30%	6.30%
Debt, maturity date		Jan. 15, 2019

[1] Short-term debt as of June 30, 2018 consists of Devon’s $20 million of 8.25% senior notes due July 1, 2018, $95 million of 2.25% senior notes due December 15, 2018 and $162 million of 6.30% senior notes due January 15, 2019.