XML 52 R38.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Regulatory Assets and Liabilities (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2017
Regulatory Assets [Line Items] |
Schedule of Regulatory Assets and Liabilities [Table Text Block] | Regulatory assets and liabilities consist of the following (dollars in millions):
| Weighted Average Remaining Life (1) |  | As of December 31,
| 2017 |  | 2016
| Current |  | Noncurrent |  | Current |  | Noncurrent
Regulatory assets: |  |  |  |  |  |  |  |  |
Price risk management (2) | 6 years |  | $ | 53 |  |  | $ | 151 |  |  | $ | 26 |  |  | $ | 120 |
Pension and other postretirement plans (2) | (3) |  | — |  |  | 218 |  |  | — |  |  | 235 |
Deferred income taxes (6) | (4) |  | — |  |  | — |  |  | — |  |  | 86 |
Debt issuance costs (2) | 6 years |  | — |  |  | 19 |  |  | — |  |  | 22 |
Other (5) | Various |  | 9 |  |  | 50 |  |  | 10 |  |  | 35 |
Total regulatory assets |  |  | $ | 62 |  |  | $ | 438 |  |  | $ | 36 |  |  | $ | 498 |
Regulatory liabilities: |  |  |  |  |  |  |  |  |
Asset retirement removal costs (6) | (4) |  | $ | — |  |  | $ | 933 |  |  | $ | — |  |  | $ | 887 |
Deferred income taxes (6) | (4) |  | — |  |  | 277 |  |  | — |  |  | — |
Trojan decommissioning activities | 5 years |  | 3 |  |  | — |  |  | 18 |  |  | — |
Asset retirement obligations (6) | (4) |  | — |  |  | 52 |  |  | — |  |  | 49 |
Other | Various |  | 28 |  |  | 26 |  |  | 33 |  |  | 22 |
Total regulatory liabilities |  |  | $ | 31 |  | (7) | $ | 1,288 |  |  | $ | 51 |  | (7) | $ | 958 |
(1) | As of December 31, 2017.
(2) | Does not include a return on investment.
(3) | Recovery expected over the average service life of employees.
(4) | Recovery or refund expected over the estimated lives of the net balance.
(5) | Of the total other unamortized regulatory asset balances, a return is recorded on $51 million and $44 million as of December 31, 2017 and 2016, respectively.
(6) | Included in rate base for ratemaking purposes.
(7) | Included in Accrued expenses and other current liabilities on the consolidated balance sheets.

X
- Definition Tabular disclosure of assets and liabilities that are created in connection with regulatory accounting [Table Text Block] + References No definition available. + Details
Name: | por_ScheduleOfRegulatoryAssetsAndLiabilitiesTableTextBlock
Namespace Prefix: | por_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
Name: | us-gaap_RegulatoryAssetLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration