Fair Value Measurement of Assets and Liabilities (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivatives	$ 43
Derivative liabilities	1
Fair Value, Measurements, Recurring
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Cash and cash equivalents	975	$ 2,202
Total financial assets	4,135	8,812
Fair Value, Measurements, Recurring | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	1,850	2,713
Fair Value, Measurements, Recurring | Derivatives
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivatives	349	262
Fair Value, Measurements, Recurring | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	961	3,635
Fair Value, Measurements, Recurring | Other Current Liabilities
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative liabilities	25	48
Fair Value, Measurements, Recurring | Restricted cash | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	21	17
Fair Value, Measurements, Recurring | Corporate debt securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	1,654	2,606
Fair Value, Measurements, Recurring | Corporate debt securities | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	961	3,635
Fair Value, Measurements, Recurring | Government and agency securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	175	90
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Cash and cash equivalents	975	2,052
Total financial assets	996	2,069
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	21	17
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Derivatives
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivatives	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Other Current Liabilities
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Restricted cash | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	21	17
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Corporate debt securities | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | Government and agency securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	150
Total financial assets	2,858	6,595
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	1,829	2,696
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Derivatives
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivatives	68	114
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	961	3,635
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Other Current Liabilities
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative liabilities	25	48
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Restricted cash | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	1,654	2,606
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Corporate debt securities | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	961	3,635
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | Government and agency securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	175	90
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Cash and cash equivalents	0	0
Total financial assets	281	148
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Derivatives
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivatives	281	148
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Other Current Liabilities
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Derivative liabilities	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Restricted cash | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Corporate debt securities | Long-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | Government and agency securities | Short-term Investments
Fair Value, Assets Measured on Recurring Basis, Financial Statement Captions [Line Items]
Investments	0	0
Warrant | Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3)
Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward]
Beginning balance	148	0
Recognition of warrant	0	44
Change in fair value	133	104
Ending balance	$ 281	$ 148