Financial Instruments and Risk Management (Tables)

12 Months Ended

Dec. 31, 2015

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Available-for-sale Securities

are accounted for as available-for-sale and recorded at fair value, and are classified as Level 2 assets.

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, 2015								December 31, 2014
Millions of dollars	Level 1		Level 2		Total fair value		Carrying value		Level 1		Level 2		Total fair value		Carrying value
Long-term debt	$	1,009	$	14,947	$	15,956	$	15,346	$	4,822	$	4,257	$	9,079	$	7,779