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Acquisitions and Investments - Additional Information (Detail) $ in Millions | 12 Months Ended
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Dec. 31, 2016 USD ($) Acquisition | Dec. 31, 2015 USD ($) Acquisition | Dec. 31, 2014 USD ($) Acquisition
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |
Aggregate cash investment of acquisitions | $ 230 | $ 86 | $ 291
Goodwill | $ 6,067 | $ 6,980 | $ 8,539
All Other Acquisitions [Member] |  |  |
Acquired Finite-Lived Intangible Assets [Line Items] |  |  |
Acquisitions completed | Acquisition | 10 | 7 | 10
Aggregate cash investment of acquisitions | $ 230 | $ 86 | $ 291
Business acquisition Nov stock issued | 18 |  |
Intangible assets | 24 | 13 | 59
Goodwill | $ 152 | $ 51 | $ 167

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