CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Jun. 30, 2020	Dec. 31, 2019
Accounts receivable, allowance	$ 115	$ 41
Treasury stock - Common stock, Shares	130,670,000	126,893,000
Series A Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.001	$ 0.001
Preferred stock, shares authorized (in shares)	100,000,000	100,000,000
Preferred stock, shares issued (in shares)	1,200,000	0
Preferred stock, shares outstanding (in shares)	1,200,000	0
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized shares (in shares)	400,000,000	400,000,000
Common stock, shares issued (in shares)	12,800,000	12,800,000
Common stock, shares outstanding (in shares)	5,523,000	5,523,000
Treasury stock - Common stock, Shares	7,300,000	7,300,000
Common stock
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized shares (in shares)	1,600,000,000	1,600,000,000
Common stock, shares issued (in shares)	259,085,000	256,692,000
Common stock, shares outstanding (in shares)	135,691,000	137,076,000