Property, plant and equipment (Detail) - USD ($)
$ in Millions |
Dec. 31, 2018 |
Dec. 31, 2017 |
| Insurance and Other [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
$ 39,827
|
$ 37,641
|
| Property, plant and equipment, accumulated depreciation |
(19,199)
|
(17,773)
|
| Total property, plant and equipment, net |
20,628
|
19,868
|
| Insurance and Other [Member] | Land [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
2,536
|
2,523
|
| Insurance and Other [Member] | Buildings and improvements [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
9,959
|
9,409
|
| Insurance and Other [Member] | Machinery and equipment [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
22,574
|
21,190
|
| Insurance and Other [Member] | Furniture, fixtures and other [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
4,758
|
4,519
|
| Railroad [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
73,189
|
70,940
|
| Property, plant and equipment, accumulated depreciation |
(10,004)
|
(8,627)
|
| Total property, plant and equipment, net |
63,185
|
62,313
|
| Railroad [Member] | Land, track structure and other roadway [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
59,509
|
57,408
|
| Railroad [Member] | Locomotives, freight cars and other equipment [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
13,016
|
12,543
|
| Railroad [Member] | Construction in progress [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
664
|
989
|
| Utilities and Energy [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
96,246
|
91,891
|
| Property, plant and equipment, accumulated depreciation |
(27,651)
|
(26,020)
|
| Total property, plant and equipment, net |
68,595
|
65,871
|
| Utilities and Energy [Member] | Utility generation, transmission and distribution systems [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
77,288
|
74,660
|
| Utilities and Energy [Member] | Interstate natural gas pipeline assets [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
7,524
|
7,176
|
| Utilities and Energy [Member] | Independent power plants and other assets [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
8,324
|
7,499
|
| Utilities and Energy [Member] | Construction in progress [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Property, plant and equipment, gross |
3,110
|
2,556
|
| Railroad, Utilities and Energy [Member] |
|
|
| Property, Plant and Equipment [Line Items] |
|
|
| Total property, plant and equipment, net |
$ 131,780
|
$ 128,184
|