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

9 Months Ended

Sep. 30, 2014

Fair Value Disclosures [Abstract]

Available-for-sale Securities

At September 30, 2014, we held $280 million of investments in fixed income securities with maturities ranging from less than one year to November 2019, compared to $373 million of investments in fixed income securities held at December 31, 2013. These securities are accounted for as available-for-sale and recorded at fair value as follows:

	September 30, 2014						December 31, 2013
Millions of dollars	Level 1		Level 2		Total		Level 1		Level 2		Total
Fixed income securities:
U.S. treasuries (a)	$	—	$	—	$	—	$	100	$	—	$	100
Other (b)	—		280		280		—		273		273
Total	$	—	$	280	$	280	$	100	$	273	$	373

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

(b) Of these securities, $131 million are classified as “Other current assets” and $149 million are classified as “Other assets” on our condensed consolidated balance sheets as of September 30, 2014, compared to $139 million classified as “Other current assets” and $134 million classified as “Other assets” as of December 31, 2013. 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:

	September 30, 2014								December 31, 2013
Millions of dollars	Level 1		Level 2		Total fair value		Carrying value		Level 1		Level 2		Total fair value		Carrying value
Long-term debt	$	4,860	$	4,220	$	9,080	$	7,816	$	8,405	$	292	$	8,697	$	7,816