Fair Value Measurements (Financial Assets And (Liabilities) Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions | Sep. 30, 2017 | Dec. 31, 2016 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | $ 866 | |
Trading securities | 25 | $ 25 |
Equity and Cost Method Investments | 72 | |
Recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 407 | 755 |
Time deposits | 359 | 806 |
Available-for-sale investment securities | 2,075 | 2,264 |
Total | 3,836 | 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 | 109 | 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 | (2) | (4) |
Recurring [Member] | Other Noncurrent Assets [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, assets | 24 | 17 |
Recurring [Member] | Other Noncurrent Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | (2) | |
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 | 656 | 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 |
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 | 547 | 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 | 288 | 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 | 133 | 115 |
Recurring [Member] | Money Market Funds [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 317 | 624 |
Recurring [Member] | Bank Deposits [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 80 | |
Recurring [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 10 | 131 |
Recurring [Member] | Level 1 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 317 | 624 |
Time deposits | 0 | 0 |
Available-for-sale investment securities | 574 | 558 |
Total | 891 | 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] | Other Noncurrent Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | 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 | 574 | 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 |
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 | 317 | 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 | 90 | 131 |
Time deposits | 359 | 806 |
Available-for-sale investment securities | 1,501 | 1,706 |
Total | 2,945 | 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 | 109 | 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 | (2) | (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 | 24 | 17 |
Recurring [Member] | Level 2 [Member] | Other Noncurrent Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | (2) | |
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 | 82 | 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 |
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 | 547 | 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 | 288 | 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 | 133 | 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] | Bank Deposits [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 80 | |
Recurring [Member] | Level 2 [Member] | Commercial Paper [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Cash equivalents | 10 | 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 |
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] | Other Noncurrent Liabilities [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Derivative financial instruments, liabilities | 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 | |
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 | 677 | |
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 | 396 | |
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 | 281 | |
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 |
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 | 677 | 40 |
Investments | 3,111 | 3,110 |
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 | 396 | |
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 | 281 | |
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] | 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 | 574 | 558 |
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 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 2 [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 677 | 40 |
Investments | 2,537 | 2,552 |
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 | 396 | |
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 | 281 | |
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 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] | 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] | 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 |
Long-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 | 189 | |
Long-term investments [Member] | Recurring [Member] | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | |
Held-to-maturity Securities, Fair Value | 189 | |
Investments | 189 | |
Long-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 | 189 | |
Long-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 | |
Investments | 0 | |
Long-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 | |
Long-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 | 189 | |
Investments | 189 | |
Long-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 | 189 | |
Long-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 | |
Investments | 0 | |
Long-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 | |