Accounts Payable and Other Current Liabilities (Details) - USD ($) $ in Millions	Jun. 30, 2018	Dec. 31, 2017
Accounts Payable and Other Current Liabilities [Abstract]
Accounts payable	$ 412	$ 359
Accrued sales and use taxes	262	218
Accrued marketing and commissions, current	197	190
Employee-related Liabilities, Current	176	176
Deferred Revenue, Current	247	135
Public liability and property damage insurance liabilities, current	144	145
Accrued Insurance, Current	102	103
Other	292	293
Accounts payable and other current liabilities	$ 1,832	$ 1,619