Business Segments - Schedule of Property and Equipment, Net by Country (Details) - USD ($) $ in Millions	Dec. 31, 2016	Dec. 31, 2015
Schedule of Property and Equipment, Net by Country [Line Items]
Property and equipment, net	$ 8,930	$ 9,119
United States [member]
Schedule of Property and Equipment, Net by Country [Line Items]
Property and equipment, net	8,438	8,612
Rest of world [member]
Schedule of Property and Equipment, Net by Country [Line Items]
Property and equipment, net	$ 492	$ 507