Energy & Transportation sales (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Energy and transportation sales
Sales and revenues	$ 12,889	$ 9,997	$ 24,776	$ 20,632
Energy & Transportation
Energy and transportation sales
Sales and revenues	4,120	3,541	7,778	7,159
Energy & Transportation | Oil And Gas Customer
Energy and transportation sales
Sales and revenues	1,137	1,027	2,052	1,888
Energy & Transportation | Power generation
Energy and transportation sales
Sales and revenues	1,052	895	2,015	1,749
Energy & Transportation | Industrial
Energy and transportation sales
Sales and revenues	899	678	1,712	1,479
Energy & Transportation | Transportation
Energy and transportation sales
Sales and revenues	$ 1,032	$ 941	$ 1,999	$ 2,043