Fair Value of Financial Instruments Fair value by balance sheet grouping table (Tables)

3 Months Ended

Mar. 31, 2013

Fair Value Disclosures [Abstract]

Available-for-sale Securities

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

	March 31, 2013						December 31, 2012
Millions of dollars	Level 1		Level 2		Total		Level 1		Level 2		Total
Fixed Income Securities:
U.S. treasuries (a)	$	150	$	—	$	150	$	150	$	—	$	150
Other (b)	—		268		268		—		248		248
Total	$	150	$	268	$	418	$	150	$	248	$	398

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

(b) Of these securities, $144 million are classified as “Other current assets” and $124 million are classified as “Other assets” on our condensed consolidated balance sheets as of March 31, 2013, compared to $120 million classified as “Other current assets” and $128 million classified as “Other assets” as of December 31, 2012. These securities consist primarily of municipal bonds, corporate bonds, and other debt instruments.

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block]

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

	March 31, 2013								December 31, 2012
Millions of dollars	Level 1		Level 2		Total fair value		Carrying value		Level 1		Level 2		Total fair value		Carrying value
Long-term debt	$	2,295	$	3,982	$	6,277	$	4,820	$	1,112	$	5,272	$	6,384	$	4,820