Property and Equipment - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Property, Plant and Equipment [Abstract]
Depreciation expense	$ 12,138	$ 8,831	$ 6,362
Amortization of property and equipment acquired under capital leases	7,300	5,400	$ 3,800
Gross assets under capital leases	36,100	26,400
Accumulated depreciation associated with capital leases	19,800	13,400
Gross assets under finance leases	7,500	5,400
Accumulated depreciation associated with finance leases	$ 1,100	$ 635