Asset Retirement Obligations and Accrued Environmental Costs (Tables)

12 Months Ended

Dec. 31, 2019

Asset Retirement Obligation and Accrual for Environmental Cost Disclosure [Abstract]

Schedule of Asset Retirement Obligations and Accrual for Environmental Costs

Asset retirement obligations and accrued environmental costs at December 31 were:

	Millions of Dollars
	2019			2018
Asset retirement obligations	$	280		261
Accrued environmental costs	441			447
Total asset retirement obligations and accrued environmental costs	721			708
Asset retirement obligations and accrued environmental costs due within one year*	(83		)	(84	)
Long-term asset retirement obligations and accrued environmental costs	$	638		624

* Classified as a current liability on the consolidated balance sheet, under the caption “Other accruals.”

Schedule of Change in Asset Retirement Obligation

During the years ended December 31, 2019 and 2018, our overall asset retirement obligation changed as follows:

	Millions of Dollars
	2019			2018
Balance at January 1	$	261		268
Accretion of discount	10			10
Changes in estimates of existing obligations	31			3
Spending on existing obligations	(22		)	(15	)
Foreign currency translation	—			(5	)
Balance at December 31	$	280		261