Supplemental Financial Information - Depreciation, Amortization and Impairment (Detail) - USD ($) $ in Millions |
12 Months Ended | ||||
|---|---|---|---|---|---|
Dec. 31, 2018 |
Dec. 31, 2017 |
Dec. 31, 2016 |
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| Property, Plant and Equipment [Line Items] | |||||
| Depreciation of property, plant and equipment | $ 478 | $ 611 | $ 609 | ||
| Amortization of intangible assets | 1,509 | 1,539 | |||
| Depreciation, amortization and impairment | 1,987 | 2,173 | 2,205 | ||
| Software [Member] | |||||
| Property, Plant and Equipment [Line Items] | |||||
| Amortization of intangible assets | 8 | 21 | 24 | ||
| Other Intangible Assets [Member] | |||||
| Property, Plant and Equipment [Line Items] | |||||
| Amortization of intangible assets | [1] | $ 1,501 | $ 1,541 | $ 1,572 | |
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