Property, Plant, and Equipment (Tables)

12 Months Ended

Dec. 31, 2017

Property, Plant and Equipment [Abstract]

Property, plant, and equipment

Property, plant and equipment were composed of the following:

	December 31
Millions of dollars	2017		2016
Land	$	248	$	228
Buildings and property improvements	3,460		3,399
Machinery, equipment and other	17,062		16,103
Total	20,770		19,730
Less accumulated depreciation	12,249		11,198
Net property, plant and equipment	$	8,521	$	8,532

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
	2017	2016
1    -   10 years	11%	11%
11    -   20 years	42%	42%
21    -   30 years	22%	22%
31    -   40 years	25%	25%

	Machinery, Equipment and Other
	2017	2016
1    -    5 years	35%	34%
6    -   10 years	56%	57%
11    -   20 years	9%	9%