XML 65 R52.htm IDEA: XBRL DOCUMENT v3.7.0.1
Investments - Additional Information (Details) - USD ($)
$ in Millions
3 Months Ended
Mar. 31, 2017
Dec. 31, 2016
Investments, Debt and Equity Securities [Abstract]    
Short-term restricted cash $ 19 $ 17
Fair Value, Option, Quantitative Disclosures [Line Items]    
Estimated fair value 4,589 4,501
Cost method investments 60 50
Fair Value Option, Foreign Currency Denominated Investments    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Estimated fair value 472 $ 356
Fair Value Option, Foreign Currency Denominated Investments | Other Income (Expense)    
Fair Value, Option, Quantitative Disclosures [Line Items]    
Net gains from fair value changes $ 6