Other Financial Data - Schedule of Allowance for Doubtful Accounts (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020	Mar. 31, 2021	Dec. 31, 2020	Mar. 31, 2020	Dec. 31, 2019
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Provision	$ 21	$ 6	$ 27	$ 15
Accounts written off, net of recoveries	(19)	(3)	(23)	(11)
Foreign currency translation and other	(1)	0	0	3
Balance at end of period	102	84	102	84
Cumulative adjustment amount to decrease retained earnings	(4,567)	(3,695)	(4,567)	(3,695)	$ (4,361)	$ (3,583)	$ (3,260)	$ (3,443)
Retained Earnings
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Cumulative adjustment amount to decrease retained earnings	(1,823)	(1,751)	(1,823)	(1,751)	$ (1,801)	$ (1,042)	$ (1,455)	$ (1,248)
Cumulative Effect, Period Of Adoption, Adjusted Balance
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Balance at beginning of period	$ 101	$ 81	$ 98	$ 77