Property, Plant And Equipment (Narrative) (Detail) - USD ($) $ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
|---|---|---|
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | $ 61,213 | $ 40,538 |
| Property, plant and equipment, accumulated depreciation | 16,155 | 14,095 |
| Assets held under capital leases | ||
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | 786 | 602 |
| Property, plant and equipment, accumulated depreciation | 202 | 248 |
| Construction in progress | ||
| Property, Plant and Equipment [Line Items] | ||
| Property, plant and equipment, gross | $ 3,490 | $ 2,200 |