Fair Value Measurements (Valuation Of Financial Instruments By Pricing Categories) (Details) - USD ($) $ in Millions | 9 Months Ended | 12 Months Ended | | |
Sep. 30, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Dec. 31, 2015 |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Cash and cash equivalents | $ 2,592 | $ 3,316 | $ 2,953 | $ 3,379 |
Assets | | | | |
Available-for-sale Securities, Current | 97 | 68 | | |
Investments Fair Value Disclosure | 2,891 | 3,580 | | |
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration [Abstract] | | | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 188 | 198 | | |
Interest Rate Swap [Member] | | | | |
Assets | | | | |
Derivative Asset | 0 | 0 | | |
Fair Value, Inputs, Level 1 | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Cash and cash equivalents | 2,592 | 3,316 | | |
Assets | | | | |
Investments Fair Value Disclosure | 2,706 | 3,410 | | |
Deferred compensation arrangements | 114 | 94 | | |
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration [Abstract] | | | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 114 | 94 | | |
Fair Value, Inputs, Level 1 | Trading marketable securities | | | | |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] | | | | |
Trading marketable securities | 114 | 94 | | |
Fair Value, Inputs, Level 2 | | | | |
Assets | | | | |
Investments Fair Value Disclosure | 185 | 170 | | |
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration [Abstract] | | | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | 41 | 18 | | |
Fair Value, Inputs, Level 2 | Foreign currency exchange forward contracts | | | | |
Assets | | | | |
Derivative Asset | 38 | 45 | | |
Liabilities | | | | |
Foreign currency exchange forward contracts | 41 | 18 | | |
Fair Value, Inputs, Level 2 | Interest Rate Swap [Member] | | | | |
Assets | | | | |
Derivative Asset | 50 | 57 | | |
Fair Value, Inputs, Level 2 | Available-for-sale marketable securities: | | | | |
Assets | | | | |
Available-for-sale Securities, Current | 97 | 68 | | |
Fair Value, Inputs, Level 2 | Available-for-sale marketable securities: | Corporate and asset-backed debt securities | | | | |
Assets | | | | |
Available-for-sale Securities, Current | 33 | 25 | | |
Fair Value, Inputs, Level 2 | Available-for-sale marketable securities: | United States agency debt securities | | | | |
Assets | | | | |
Available-for-sale Securities, Current | 19 | 9 | | |
Fair Value, Inputs, Level 2 | Available-for-sale marketable securities: | United States Treasury debt securities | | | | |
Assets | | | | |
Available-for-sale Securities, Current | 24 | 16 | | |
Fair Value, Inputs, Level 2 | Available-for-sale marketable securities: | Certificates of deposit | | | | |
Assets | | | | |
Available-for-sale Securities, Current | 21 | 18 | | |
Fair Value, Inputs, Level 3 | | | | |
Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration [Abstract] | | | | |
Beginning | 86 | 56 | | |
Additions | 5 | 49 | | |
Change in estimate | (2) | (7) | | |
Settlements | (56) | (12) | | |
Ending | 33 | 86 | | |
Financial and Nonfinancial Liabilities, Fair Value Disclosure | $ 33 | $ 86 | | |