Fair Value Measurements and Disclosures (Details 2) (USD $) In Millions, unless otherwise specified	Mar. 31, 2013		Dec. 31, 2012
Carrying Amount
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt Net Of Unamortized Discount	$ 3,798	[1]	$ 3,797	[1]
Fair Value
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Long Term Debt Net Of Unamortized Discount	$ 4,539	[1]	$ 4,570	[1]

[1] Excludes Aseng FPSO lease obligation. No floating rate debt was outstanding at March 31, 2013 or December 31, 2012.