Stockholders' Equity - Summary of Noncontrolling Interest Balances By Projects (Details) - USD ($)
$ in Millions |
Sep. 30, 2019 |
Dec. 31, 2018 |
Sep. 30, 2018 |
Dec. 31, 2017 |
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
$ 1,040
|
$ 1,112
|
$ 1,045
|
$ 1,254
|
| Logan's Gap |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
123
|
132
|
|
|
| Panhandle 1 |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
118
|
131
|
|
|
| Panhandle 2 |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
162
|
176
|
|
|
| Post Rock |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
101
|
116
|
|
|
| Amazon Wind |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
92
|
101
|
|
|
| Broadview Project |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
243
|
257
|
|
|
| Futtsu |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
9
|
10
|
|
|
| Meikle |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
44
|
57
|
|
|
| MSM |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
38
|
37
|
|
|
| Stillwater |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
92
|
95
|
|
|
| Belle River |
|
|
|
|
| Noncontrolling Interest [Line Items] |
|
|
|
|
| Noncontrolling interest |
$ 18
|
$ 0
|
|
|