Prepaid Expenses and Other Assets (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Deferred Costs, Capitalized, Prepaid, and Other Assets Disclosure [Abstract]
Equipment	$ 289	$ 300
Insurance	12	18
Advertising reimbursements	9	11
Income taxes	4	4
Other	44	42
Prepaid expenses and other assets	358	$ 375
Increase (decrease) in prepaid expense and other assets, equipment, placed deposits	(50)
Increase (decrease) in prepaid expense and other assets, equipment purchase	$ (61)