Fair Value Measurements (Financial Assets And (Liabilities) Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Mar. 31, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | $ 386 | |
Trading securities | 25 | $ 25 |
Equity and Cost Method Investments | 65 | |
Held-to-maturity Securities, Current | 341 | 40 |
Available-for-sale securities, current | 1,953 | 2,264 |
U.S. Treasury And Agency Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, current | 635 | 602 |
Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 45 | |
Available-for-sale securities, current | 451 | 405 |
Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, current | 455 | 911 |
Asset-Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, current | 289 | 231 |
Municipal Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, current | 123 | 115 |
Mutual Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale securities, current | | 25 |
Recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 358 | 755 |
Time deposits | 647 | 806 |
Available-for-sale investment securities | 1,953 | 2,264 |
Held-to-maturity Securities, Fair Value | 45 | |
Investments | 45 | |
Total | 3,487 | 3,912 |
Recurring [Member] | Other Current Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 102 | 34 |
Recurring [Member] | Accrued Expenses And Other Current Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | (13) | (4) |
Recurring [Member] | Other Noncurrent Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 54 | 17 |
Recurring [Member] | U.S. Treasury And Agency Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 635 | 602 |
Recurring [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 451 | 405 |
Held-to-maturity Securities, Fair Value | 45 | |
Recurring [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 455 | 911 |
Recurring [Member] | Asset-Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 289 | 231 |
Recurring [Member] | Municipal Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 123 | 115 |
Recurring [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 350 | 624 |
Recurring [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 8 | 131 |
Recurring [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 350 | 624 |
Time deposits | 0 | 0 |
Available-for-sale investment securities | 544 | 558 |
Held-to-maturity Securities, Fair Value | 0 | |
Investments | 0 | |
Total | 894 | 1,182 |
Recurring [Member] | Level 1 [Member] | Other Current Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 0 | 0 |
Recurring [Member] | Level 1 [Member] | Accrued Expenses And Other Current Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | 0 | 0 |
Recurring [Member] | Level 1 [Member] | Other Noncurrent Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 0 | 0 |
Recurring [Member] | Level 1 [Member] | U.S. Treasury And Agency Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 544 | 558 |
Recurring [Member] | Level 1 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Held-to-maturity Securities, Fair Value | 0 | |
Recurring [Member] | Level 1 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 1 [Member] | Asset-Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 1 [Member] | Municipal Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 1 [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 350 | 624 |
Recurring [Member] | Level 1 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 0 | 0 |
Recurring [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 8 | 131 |
Time deposits | 647 | 806 |
Available-for-sale investment securities | 1,409 | 1,706 |
Held-to-maturity Securities, Fair Value | 45 | |
Investments | 45 | |
Total | 2,593 | 2,730 |
Recurring [Member] | Level 2 [Member] | Other Current Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 102 | 34 |
Recurring [Member] | Level 2 [Member] | Accrued Expenses And Other Current Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | (13) | (4) |
Recurring [Member] | Level 2 [Member] | Other Noncurrent Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 54 | 17 |
Recurring [Member] | Level 2 [Member] | U.S. Treasury And Agency Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 91 | 44 |
Recurring [Member] | Level 2 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 451 | 405 |
Held-to-maturity Securities, Fair Value | 45 | |
Recurring [Member] | Level 2 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 455 | 911 |
Recurring [Member] | Level 2 [Member] | Asset-Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 289 | 231 |
Recurring [Member] | Level 2 [Member] | Municipal Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 123 | 115 |
Recurring [Member] | Level 2 [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | | 0 |
Recurring [Member] | Level 2 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 8 | 131 |
Recurring [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | | 0 |
Time deposits | 0 | 0 |
Available-for-sale investment securities | 0 | 0 |
Held-to-maturity Securities, Fair Value | 0 | |
Investments | 0 | |
Total | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Other Current Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Accrued Expenses And Other Current Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Other Noncurrent Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 0 | 0 |
Recurring [Member] | Level 3 [Member] | U.S. Treasury And Agency Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | |
Held-to-maturity Securities, Fair Value | 0 | |
Recurring [Member] | Level 3 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Asset-Backed Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Municipal Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Available-for-sale investment securities | 0 | 0 |
Recurring [Member] | Level 3 [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | | 0 |
Recurring [Member] | Level 3 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 0 | 0 |
Short-term Investments [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 341 | |
Held-to-maturity Securities, Current | 341 | |
Short-term Investments [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 96 | |
Held-to-maturity Securities, Current | 96 | |
Short-term Investments [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | | 40 |
Held-to-maturity Securities, Current | | 40 |
Short-term Investments [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 245 | |
Held-to-maturity Securities, Current | 245 | |
Short-term Investments [Member] | Recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 341 | 40 |
Investments | 2,941 | 3,110 |
Short-term Investments [Member] | Recurring [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 96 | |
Short-term Investments [Member] | Recurring [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | | 40 |
Short-term Investments [Member] | Recurring [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 245 | |
Short-term Investments [Member] | Recurring [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 0 | 0 |
Investments | 544 | 558 |
Short-term Investments [Member] | Recurring [Member] | Level 1 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 0 | |
Short-term Investments [Member] | Recurring [Member] | Level 1 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | | 0 |
Short-term Investments [Member] | Recurring [Member] | Level 1 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 0 | |
Short-term Investments [Member] | Recurring [Member] | Level 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 341 | 40 |
Investments | 2,397 | 2,552 |
Short-term Investments [Member] | Recurring [Member] | Level 2 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 96 | |
Short-term Investments [Member] | Recurring [Member] | Level 2 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | | 40 |
Short-term Investments [Member] | Recurring [Member] | Level 2 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 245 | |
Short-term Investments [Member] | Recurring [Member] | Level 3 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 0 | 0 |
Investments | 0 | 0 |
Short-term Investments [Member] | Recurring [Member] | Level 3 [Member] | Corporate And Other Debt Securities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 0 | |
Short-term Investments [Member] | Recurring [Member] | Level 3 [Member] | Certificates of Deposit and Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | | $ 0 |
Short-term Investments [Member] | Recurring [Member] | Level 3 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | $ 0 | |