Short-term borrowings (Details) - USD ($) $ in Millions	Dec. 31, 2017	Dec. 31, 2016
Short-term borrowings:
Short-term borrowings	$ 4,837	$ 7,303
Notes payable to banks
Short-term borrowings:
Weighted-average interest rates on short-term borrowings (as a percent)	5.20%	7.00%
Commercial paper
Short-term borrowings:
Weighted-average interest rates on short-term borrowings (as a percent)	1.10%	0.90%
Demand notes
Short-term borrowings:
Weighted-average interest rates on short-term borrowings (as a percent)	1.10%	0.90%
Machinery, Energy & Transportation
Short-term borrowings:
Short-term borrowings	$ 1	$ 209
Machinery, Energy & Transportation | Notes payable to banks
Short-term borrowings:
Short-term borrowings	1	59
Machinery, Energy & Transportation | Commercial paper
Short-term borrowings:
Short-term borrowings	0	150
Financial Products
Short-term borrowings:
Short-term borrowings	4,836	7,094
Financial Products | Notes payable to banks
Short-term borrowings:
Short-term borrowings	675	553
Financial Products | Commercial paper
Short-term borrowings:
Short-term borrowings	3,680	5,985
Financial Products | Demand notes
Short-term borrowings:
Short-term borrowings	$ 481	$ 556