Income Taxes, Income Statement Components of Tax Expense (Benefit) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Components of Income Tax Expense (Benefit)
U.S. operations	$ 3,168	$ 2,283	$ 1,733
International operations	1,064	924	1,449
Income before income tax expense (benefit)	$ 4,232	$ 3,207	$ 3,182