Supplemental Financial Information - Cash Flows (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flow disclosures
Payment of cash taxes	$ 990	$ 700
Net tax benefits primarily as a result of the resolution of various tax positions related to prior years related to discontinued operation		20
Defined Benefit Plans
Cash flow disclosures
Pension contributions	$ 366	$ 350