Concentration of credit risk (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Risks and Uncertainties [Abstract]
Derivative contracts, maximum exposure to credit loss	$ 74	$ 96

The maximum exposure to credit loss on derivative contracts before the application of any master netting agreements.

No definition available.

Name:	cat_DerivativesMaximumExposureToCreditLoss
Namespace Prefix:	cat_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant