Property and Equipment - Depreciation Expense and Capitalized Interest (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 251	$ 81	$ 515	$ 168
Capitalized interest	$ 1	$ 1	$ 3	$ 2