Financial Instruments and Risk Management (Tables)

12 Months Ended

Dec. 31, 2018

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of Carrying Values and Estimated Fair Values of Debt Instruments

The carrying amount and fair value of our total debt, including short-term borrowings and current maturities of long term debt, is as follows:

	December 31, 2018								December 31, 2017
Millions of dollars	Level 1		Level 2		Total fair value		Carrying value		Level 1		Level 2		Total fair value		Carrying value
Total debt	$	6,726	$	4,150	$	10,876	$	10,457	$	3,285	$	9,172	$	12,457	$	10,942