Accounts Payable and Other Accrued Liabilities - Summary of Accounts Payable and Other Accrued Liabilities (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Payables And Accruals [Line Items]
Accounts payable, including $23 and $16, respectively, due to related parties	$ 200	$ 67
Sales taxes and vehicle licenses and fees	136	71
Accrued compensation and benefits	65	34
Accrued interest expense	56	20
Accrued property and equipment	51	33
Reserve for returns and cancellations	45	25
Accrued advertising costs	38	21
Customer deposits	32	17
Other accrued liabilities	77	54
Total accounts payable and accrued liabilities	700	342
Related Party
Payables And Accruals [Line Items]
Accounts payable, including $23 and $16, respectively, due to related parties	23	16
Total accounts payable and accrued liabilities	$ 23	$ 16