Fair Value Measurements

12 Months Ended

Dec. 31, 2011

Fair Value, Assets and Liabilities Measured on Recurring Basis [Abstract]

Fair Value Disclosures [Text Block]

(3)FAIR VALUE MEASUREMENTS

Fair value is measured based on an exit price, representing the amount that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. As a basis for considering such assumptions, a three-tiered fair value hierarchy is established, which prioritizes the inputs used in measuring fair value as follows: (Level 1) observable inputs such as quoted prices in active markets; (Level 2) inputs, other than the quoted prices in active markets that are observable, either directly or indirectly; and (Level 3) unobservable inputs in which there is little or no market data, which require the reporting entity to develop its own assumptions. We had no Level 3 assets or liabilities at December 31, 2011 and 2010.

Assets and liabilities measured at fair value using the market approach valuation technique. This technique uses prices and other relevant information generated by market transactions involving identical or comparable assets or liabilities.

Assets and liabilities measured at fair value on a recurring basis at December 31, 2011 and 2010 are as follows:

	Total Cost Basis				Quoted Prices In Active Markets for Identical Assets (Level 1)				Significant Other Observable Inputs (Level 2)					Total Fair Value
Millions of dollars	2011		2010		2011		2010		2011			2010		2011			2010
Money market funds (1)	$	340	$	414	$	340	$	414	$	—		$	—	$	340		$	414
Net derivative contracts	—		—		—		—		(57		)	125		(57		)	125
Available for sale investments	21		27		15		25		—			—		15			25

(1) Money market funds are primarily comprised of United States government obligations.