Fair Value Measurements (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Financial Assets:
Financial Assets: Crude Oil Swaps	$ 65,000,000	$ 29,000,000
Financial Assets: Crude Oil Options/Swaptions	36,000,000	4,000,000
Financial Assets: Natural Gas Swaps		81,000,000
Financial Assets: Natural Gas Options/Swaptions	65,000,000	372,000,000
Financial Liabilities:
Financial Liabilities: Crude Oil Options/Swaptions	8,000,000
Financial Liabilities: Natural Gas Options/Swaptions	13,000,000
Financial Liabilities: Foreign Currency Rate Swap	55,000,000	52,000,000
Financial Liabilities: Interest Rate Swap	4,000,000	3,000,000
Proved and Unproved Oil and Gas Properties and Other Property, Plant and Equipment Written Down during the Period - Fair Value at End of Period	1,524,000,000	1,450,000,000
Proved and Unproved Oil and Gas Properties and Other Property, Plant and Equipment Written Down During the Period - Fair value at End of Period	391,000,000	616,000,000
Pretax Impairment Charge for Proved Oil and Gas Properties and Other Property, Plant and Equipment, in which EOG utilized an accepted offer from a third-party buyer	60,000,000	278,000,000
Impairment Charge For Proved and Unproved Oil And Gas Properties And Other Property, Plant And Equipment	1,133,000,000	834,000,000
Fair Value of Debt	7,032,000,000	5,657,000,000
Total Principal Amount of Long-Term Debt	6,290,000,000	5,040,000,000
Fair Value, Inputs, Level 1 [Member]
Financial Assets:
Financial Assets: Crude Oil Swaps	0	0
Financial Assets: Crude Oil Options/Swaptions	0	0
Financial Assets: Natural Gas Swaps		0
Financial Assets: Natural Gas Options/Swaptions	0	0
Financial Liabilities:
Financial Liabilities: Crude Oil Options/Swaptions	0
Financial Liabilities: Natural Gas Options/Swaptions	0
Financial Liabilities: Foreign Currency Rate Swap	0	0
Financial Liabilities: Interest Rate Swap	0	0
Fair Value, Inputs, Level 2 [Member]
Financial Assets:
Financial Assets: Crude Oil Swaps	65,000,000	29,000,000
Financial Assets: Crude Oil Options/Swaptions	36,000,000	4,000,000
Financial Assets: Natural Gas Swaps		81,000,000
Financial Assets: Natural Gas Options/Swaptions	65,000,000	372,000,000
Financial Liabilities:
Financial Liabilities: Crude Oil Options/Swaptions	8,000,000
Financial Liabilities: Natural Gas Options/Swaptions	13,000,000
Financial Liabilities: Foreign Currency Rate Swap	55,000,000	52,000,000
Financial Liabilities: Interest Rate Swap	4,000,000	3,000,000
Fair Value, Inputs, Level 3 [Member]
Financial Assets:
Financial Assets: Crude Oil Swaps	0	0
Financial Assets: Crude Oil Options/Swaptions	0	0
Financial Assets: Natural Gas Swaps		0
Financial Assets: Natural Gas Options/Swaptions	0	0
Financial Liabilities:
Financial Liabilities: Crude Oil Options/Swaptions	0
Financial Liabilities: Natural Gas Options/Swaptions	0
Financial Liabilities: Foreign Currency Rate Swap	0	0
Financial Liabilities: Interest Rate Swap	$ 0	$ 0