Leases - Effect of Adopting New Lease Standard (Details) - USD ($) $ in Millions	Sep. 30, 2019	Jan. 01, 2019	Dec. 31, 2018
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, net	$ 14,988	$ 15,949	$ 16,045
Deferred charges and other assets	805	863	383
Accrued expenses and other current liabilities	1,300	1,250	1,217
Financing obligations	10,045	9,961	10,057
Deferred credits and other liabilities	$ 1,731	1,296	$ 849
Effect of Adoption
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Property and equipment, net		(96)
Deferred charges and other assets		480
Accrued expenses and other current liabilities		33
Financing obligations		(96)
Deferred credits and other liabilities		$ 447