Supplemental Financial Information - Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Cash flow disclosures
Payment of cash taxes	$ 125	$ 185
Discontinued operations
Cash flow disclosures
Net tax benefits primarily as a result of the resolution of various tax positions related to prior years	20
Defined Benefit Plans
Cash flow disclosures
Pension contributions	$ 320	$ 313