SAN ONOFRE NUCLEAR GENERATING STATION (SONGS) - NUCLEAR DECOMMISSIONING TRUSTS (Details) - USD ($)
$ in Millions |
3 Months Ended |
9 Months Ended |
|
Sep. 30, 2016 |
Sep. 30, 2015 |
Sep. 30, 2016 |
Sep. 30, 2015 |
Dec. 31, 2015 |
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
$ 628
|
|
$ 628
|
|
$ 660
|
| Gross unrealized gains |
447
|
|
447
|
|
423
|
| Gross unrealized losses |
(7)
|
|
(7)
|
|
(20)
|
| Estimated fair value |
1,068
|
|
1,068
|
|
1,063
|
| Proceeds from sales |
282
|
$ 210
|
486
|
$ 431
|
|
| Gross realized gains |
24
|
18
|
32
|
24
|
|
| Gross realized losses |
(3)
|
$ (6)
|
(14)
|
$ (13)
|
|
| Total debt securities [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
428
|
|
428
|
|
431
|
| Gross unrealized gains |
25
|
|
25
|
|
11
|
| Gross unrealized losses |
(4)
|
|
(4)
|
|
(13)
|
| Estimated fair value |
449
|
|
449
|
|
429
|
| U.S. government corporations and agencies [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
95
|
|
95
|
|
89
|
| Gross unrealized gains |
5
|
|
5
|
|
2
|
| Gross unrealized losses |
0
|
|
0
|
|
0
|
| Estimated fair value |
100
|
|
100
|
|
91
|
| Municipal bonds [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
150
|
|
150
|
|
148
|
| Gross unrealized gains |
11
|
|
11
|
|
8
|
| Gross unrealized losses |
0
|
|
0
|
|
0
|
| Estimated fair value |
161
|
|
161
|
|
156
|
| Other securities [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
183
|
|
183
|
|
194
|
| Gross unrealized gains |
9
|
|
9
|
|
1
|
| Gross unrealized losses |
(4)
|
|
(4)
|
|
(13)
|
| Estimated fair value |
188
|
|
188
|
|
182
|
| Equity securities [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
188
|
|
188
|
|
214
|
| Gross unrealized gains |
422
|
|
422
|
|
412
|
| Gross unrealized losses |
(3)
|
|
(3)
|
|
(7)
|
| Estimated fair value |
607
|
|
607
|
|
619
|
| Cash and cash equivalents [Member] |
|
|
|
|
|
| Schedule of Available-for-sale Securities [Line Items] |
|
|
|
|
|
| Cost |
12
|
|
12
|
|
15
|
| Gross unrealized gains |
0
|
|
0
|
|
0
|
| Gross unrealized losses |
0
|
|
0
|
|
0
|
| Estimated fair value |
$ 12
|
|
$ 12
|
|
$ 15
|