Quarterly report pursuant to Section 13 or 15(d)

Assets And Liabilities Measured At Fair Value - Realized and Unrealized Gains (Losses) on Financial Instruments (Details)

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Assets And Liabilities Measured At Fair Value - Realized and Unrealized Gains (Losses) on Financial Instruments (Details) - USD ($)
$ in Millions
 3 Months Ended
Mar. 31, 2018
Mar. 31, 2017
Oct. 17, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Realized and unrealized gains (losses) on financial instruments, net $ 153 $ (12)  
1.375% Cash Convertible Senior Notes Due 2023      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Debt instrument interest rate 1.375%   1.375%
Fair Value Option Securities      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Realized and unrealized gains (losses) on financial instruments, net $ 74 30  
Debt measured at fair value      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Realized and unrealized gains (losses) on financial instruments, net 30 (116)  
Bond Hedge Change in Fair Value      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Realized and unrealized gains (losses) on financial instruments, net 20 78  
Other derivatives      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Realized and unrealized gains (losses) on financial instruments, net $ 29 $ (4)