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Summary of Significant Accounting Policies (Tables) | 12 Months Ended
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Dec. 31, 2015
Accounting Policies [Abstract] |
Schedule of Remaining Contractual Maturities for Chattel Paper Agreements | As of December 31, 2015, the remaining contractual maturities of the chattel paper agreements were as follows:
| (In thousands) |  | 2016 |  | 2017 |  | 2018 |  | 2019 |  | 2020 |  | Thereafter |
| Repurchase-to-Maturity Transactions: |  |  |  |  |  |  |  |  |  |  |  |  |
| Loans | $ | 706 | $ | 476 | $ | 508 | $ | 477 | $ | 445 | $ | 1,059 |
Straight-Line Depreciation Rates | Provisions at composite straight-line depreciation rates ap proximate the following percentages for the cost of depreciable property:
|  | 2015 |  | 2014 |  | 2013 |  |
| Electric | 2.6 % |  | 2.6 % |  | 2.7 % |  |
| Gas | 1.7 % |  | 1.7 % |  | 1.7 % |  |
| Nonregulated | 2.4 % |  | 2.4 % |  | 2.3 % |  |

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- Definition Tabular disclosure of composite straight-line depreciation rates by segment. + References No definition available. + Details
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- Definition Tabular disclosure of the nature and risks of short-term collateralized financing obtained through repurchase agreements, securities lending transactions and repurchase-to-maturity transactions, accounted for as secured borrowings. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 7 -URI http://asc.fasb.org/extlink&oid=55761124&loc=SL34722452-111729 + Details
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