CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Accounts receivable, allowance for doubtful accounts	$ 7	$ 5
Class A Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	500,000,000	500,000,000
Common stock, shares issued (in shares)	49,314,303	49,252,671
Common stock, shares outstanding (in shares)	49,314,303	49,252,671
Class B Common Stock
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	140,000,000	140,000,000
Common stock, shares issued (in shares)	23,775,056	24,727,682
Common stock, shares outstanding (in shares)	23,775,056	24,727,682