Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Abstract]

Property, plant, and equipment

Property, plant and equipment were composed of the following:

	December 31
Millions of dollars	2018		2017
Land	$	252	$	248
Buildings and property improvements	3,461		3,460
Machinery, equipment and other	18,430		17,062
Total	22,143		20,770
Less accumulated depreciation	13,182		12,249
Net property, plant and equipment	$	8,961	$	8,521

Percentages of building and property improvements, and total machinery, and equipment and other, excluding oil and natural gas investments, depreciated over useful lives

Classes of assets are depreciated over the following useful lives:

	Buildings and Property Improvements
	2018	2017
1    -   10 years	11%	11%
11    -   20 years	42%	42%
21    -   30 years	23%	22%
31    -   40 years	25%	25%

	Machinery, Equipment and Other
	2018	2017
1    -    5 years	34%	35%
6    -   10 years	56%	56%
11    -   20 years	10%	9%