Stock-Based Compensation (Details 3) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Compensation and Retirement Disclosure [Abstract]
401K Plan Employer Matching Contribution, Percent	6.00%
401K Plan Employer Cash Contributions	$ 17		$ 14		$ 11
Deferred Compensatoin Plan Additional Information [Abstract]
Shares of common stock held by rabbi trust (in dollars per share)	$ 33.44
Deferred Compensation Arrangement Most Shares Held By Individual	700,000
Deferred Compensation Arrangement Most Shares Held By Individual Percentage	94.00%
Deferred Compensation Distribution Timeline	7 years
Deferred Compensation Arrangement Plan Distribution Amount	100,000
Deferred Compensation Arrangement Shares Sold	2,268		100		100
Deferred Compensation Arrangements Trust Plan Distribution Amount	19		17		17
Deferred Compensation Arrangement with Individual, Compensation Expense	6	[1]	8	[1]	15	[1]
Deferred Compensation Liability, Current and Noncurrent	70		60		51
Defined Benefit Pension Plans and Defined Benefit Postretirement Plans Disclosure [Abstract]
Defined Benefit Plan, Benefit Obligation	370		311
Defined Benefit Plan, Fair Value of Plan Assets	247		219
Defined Benefit Plan, Amaounts recognized in Balance Sheet	123		92
Pension and Other Postretirement Defined Benefit Plans, Liabilities, Noncurrent	116		88
Defined Benefit Plan, Net Periodic Benefit Cost	27		21		21
Defined Benefit Plan, Estimated Future Employer Contributions in Next Fiscal Year	26
Rabbi Trust Assets [Abstract]
Mutual Fund Investments	84		82
Noble Energy Common Stock (at Fair Value)	76		80
Total Rabbi Trust Assets	160		162
Liability Under Related Deferred Compensation Plan	$ 160		$ 162
Number of Shares of Noble Energy Common Stock Held by Rabbi Trust	746,672		848,940

[1] Amounts represent increases in the fair value of shares of our common stock held in a rabbi trust.