Financial Instruments and Risk Management (Tables)

12 Months Ended

Dec. 31, 2012

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Available-for-sale Securities

These securities are accounted for as available-for-sale and recorded at fair value as follows:

	December 31, 2012						December 31, 2011
Millions of dollars	Level 1		Level 2		Total		Level 1		Total
Fixed Income Securities:
U.S. treasuries (a)	$	150	—		$	150	$	150	$	150
Other (b)	—		248		248		—		—
Total	$	150	$	248	$	398	$	150	$	150

(a) These securities are classified as "Other current assets" in our consolidated balance sheets.

(b) Of these securities, $120 million are classified as “Other current assets” and $128 million are classified as “Other assets” in our consolidated balance sheets. These securities consist primarily of municipal bonds, corporate bonds, and other debt instruments.

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments

The carrying amount and fair value of our long-term debt is as follows:

	December 31, 2012								December 31, 2011
Millions of dollars	Level 1		Level 2		Total fair value		Carrying value		Level 1		Level 2		Total fair value		Carrying value
Long-term debt	$	1,112	$	5,272	$	6,384	$	4,820	$	3,555	$	2,603	$	6,158	$	4,820