Prepaid Expenses and Other Assets (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Equipment	$ 124	$ 300
Insurance	17	18
Advertising reimbursements	25	11
Income taxes	18	4
Other	60	42
Prepaid expenses and other assets	244	$ 375
Increase (decrease) in prepaid expense and other assets, equipment, new deposits	(109)
Increase (decrease) in prepaid expense and other assets, equipment purchase	$ (285)