CONSOLIDATED BALANCE SHEETS (Parenthetical) - USD ($) $ in Millions		Sep. 30, 2021	Dec. 31, 2020
Accounts receivable, allowance for doubtful accounts		$ 7	$ 5
Assets	[1]	12,845	13,382
Liabilities	[1]	14,211	14,377
Consolidated VIEs
Assets		214	233
Liabilities		96	76
Consolidated VIEs | Nonrecourse
Liabilities		$ 83	$ 60
Class A Common Stock
Common Stock, par value (in USD per share)		$ 0.01	$ 0.01
Common Stock, shares authorized (in shares)		500,000,000	500,000,000
Common Stock, shares issued (in shares)		51,710,632	49,252,671
Common Stock, shares outstanding (in shares)		51,710,632	49,252,671
Class B Common Stock
Common Stock, par value (in USD 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

[1] Our consolidated total assets as of September 30, 2021 and December 31, 2020 include total assets of variable interest entities (VIEs) of $214 million and $233 million, respectively, which can only be used to settle the obligations of the VIEs. Our consolidated total liabilities as of September 30, 2021 and December 31, 2020 include total liabilities of VIEs of $83 million and $60 million, respectively, for which the creditors of the VIEs have no recourse to us. See Note 9. Variable Interest Entities.