Consolidated Statements Of Financial Position (Unaudited) (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Statement of Financial Position [Abstract]
Accounts Receivable, Allowance for Credit Loss, Current	$ 74	$ 67
Preferred stock, par value (in dollars per share)	$ 0.10	$ 0.10
Preferred Stock, Shares Authorized	15,000,000.0	15,000,000.0
Preferred Stock, Shares Issued	0	0
Class A common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common Stock, Shares Authorized	1,000,000,000	1,000,000,000
Common Stock, Shares, Issued	541,000,000	548,000,000
Common Stock, Shares, Outstanding	541,000,000	548,000,000