Income Taxes, Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Unrecognized Tax Benefits
Unrecognized tax benefits	$ 816	$ 847	$ 897	$ 970
Tax refund claims not yet filed but that we intend to file	(28)	(26)
Interest and penalties	86	110
Liability for unrecognized tax benefits presented in our balance sheets	$ 874	$ 931