Fair Value Measurement (Details) - USD ($) $ in Millions | 3 Months Ended | 9 Months Ended | |
Sep. 30, 2015 | Sep. 30, 2015 | Dec. 31, 2014 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | $ 11,526 | $ 11,526 | $ 6,884 |
Change in fair value of contingent consideration liability | 12 | 34 | |
U.S. government securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,924 | 4,924 | 2,830 |
U.S. government agency securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,389 | 4,389 | 2,710 |
Corporate debt securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 2,213 | 2,213 | 1,344 |
Fair Value, Measurements, Recurring | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Total cash equivalents and marketable securities | 13,147 | 13,147 | 9,037 |
Contingent consideration liability | 225 | 225 | 191 |
Fair Value, Measurements, Recurring | Quoted Prices in Active Markets for Identical Assets (Level 1) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Total cash equivalents and marketable securities | 10,934 | 10,934 | 7,693 |
Contingent consideration liability | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Significant Other Observable Inputs (Level 2) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Total cash equivalents and marketable securities | 2,213 | 2,213 | 1,344 |
Contingent consideration liability | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Significant Unobservable Inputs (Level 3) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Total cash equivalents and marketable securities | 0 | 0 | 0 |
Contingent consideration liability | 225 | 225 | 191 |
Fair Value, Measurements, Recurring | U.S. government securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,924 | 4,924 | 2,830 |
Fair Value, Measurements, Recurring | U.S. government securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,924 | 4,924 | 2,830 |
Fair Value, Measurements, Recurring | U.S. government securities | Significant Other Observable Inputs (Level 2) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | U.S. government securities | Significant Unobservable Inputs (Level 3) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | U.S. government agency securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,389 | 4,389 | 2,710 |
Fair Value, Measurements, Recurring | U.S. government agency securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 4,389 | 4,389 | 2,710 |
Fair Value, Measurements, Recurring | U.S. government agency securities | Significant Other Observable Inputs (Level 2) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | U.S. government agency securities | Significant Unobservable Inputs (Level 3) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Corporate debt securities | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 2,213 | 2,213 | 1,344 |
Fair Value, Measurements, Recurring | Corporate debt securities | Quoted Prices in Active Markets for Identical Assets (Level 1) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Other Observable Inputs (Level 2) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 2,213 | 2,213 | 1,344 |
Fair Value, Measurements, Recurring | Corporate debt securities | Significant Unobservable Inputs (Level 3) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Marketable securities | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Money market funds | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Cash equivalents | 1,621 | 1,621 | 2,153 |
Fair Value, Measurements, Recurring | Money market funds | Quoted Prices in Active Markets for Identical Assets (Level 1) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Cash equivalents | 1,621 | 1,621 | 2,153 |
Fair Value, Measurements, Recurring | Money market funds | Significant Other Observable Inputs (Level 2) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Cash equivalents | 0 | 0 | 0 |
Fair Value, Measurements, Recurring | Money market funds | Significant Unobservable Inputs (Level 3) | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis | | | |
Cash equivalents | $ 0 | $ 0 | $ 0 |