Accounts Receivable, Net (Schedule of Receivables, Net) (Details) - USD ($) $ in Millions	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Receivables [Abstract]
Accounts receivable	$ 10,557	$ 9,800
Allowance for expected credit losses	(520)	(546)	$ (308)	$ (254)
Total accounts receivable, net	$ 10,037	$ 9,254