v3.4.0.3

SONGS NDT 1 (Details) - USD ($) $ in Millions | 3 Months Ended | 12 Months Ended
--- | --- | ---
Mar. 31, 2016 | Mar. 31, 2015 | Dec. 31, 2015
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | $ 662 |  |  | $ 660
Gross Unrealized Gains |  | 433 |  |  | 423
Gross Unrealized Loss |  | (13) |  |  | (20)
Estimated fair value |  | 1,082 |  |  | 1,063
Proceeds from sales | [1] | 93 |  | $ 94 |
Gross realized gains |  | 3 |  | 2 |
Gross realized losses |  | (8) |  | $ (4) |
Total Debt Securities |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 439 |  |  | 431
Gross Unrealized Gains |  | 20 |  |  | 11
Gross Unrealized Loss |  | (8) |  |  | (13)
Estimated fair value |  | 451 |  |  | 429
Debt Securities Issued By The U.S. Treasury And Other U.S. Government Corporations And Agencies |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 101 | [2] |  | 89
Gross Unrealized Gains |  | 4 | [2] |  | 2
Gross Unrealized Loss |  | 0 | [2] |  | 0
Estimated fair value |  | 105 | [2] |  | 91
Municipal Bonds |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 146 | [3] |  | 148
Gross Unrealized Gains |  | 10 | [3] |  | 8
Gross Unrealized Loss |  | 0 | [3] |  | 0
Estimated fair value |  | 156 | [3] |  | 156
Other Debt Securities |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 192 | [3] |  | 194
Gross Unrealized Gains |  | 6 | [3] |  | 1
Gross Unrealized Loss |  | (8) | [3] |  | (13)
Estimated fair value |  | 190 | [3] |  | 182
Equity Securities |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 214 |  |  | 214
Gross Unrealized Gains |  | 413 |  |  | 412
Gross Unrealized Loss |  | (4) |  |  | (7)
Estimated fair value |  | 623 |  |  | 619
Cash And Cash Equivalents |  |  |  |  |
Schedule of Available-for-sale Securities [Line Items] |  |  |  |  |
Cost |  | 9 |  |  | 15
Gross Unrealized Gains |  | 0 |  |  | 0
Gross Unrealized Loss |  | (1) |  |  | 0
Estimated fair value |  | $ 8 |  |  | $ 15
[1] | Excludes securities that are held to maturity.
[2] | Maturity dates are 2016-2065.
[3] | Maturity dates are 2016-2115.

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