Description of Business and Accounting Policies - Other Income (Expense), Net (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Accounting Policies [Abstract]
Foreign currency gains (losses)	$ (206)	$ 247	$ 21
Derivative [Line Items]
Equity Securities Gains	145	18	1
Equity Warrant
Derivative [Line Items]
Derivative gains (losses)	$ (131)	$ 109	$ 67