PSNH GENERATION ASSET SALE - PSNH Generation Assets and Liabilities (Details) - USD ($) $ in Thousands |
Mar. 31, 2017 |
Dec. 31, 2016 |
|---|---|---|
| Regulatory Assets [Line Items] | ||
| Gross Plant | $ 27,354,000 | $ 27,060,500 |
| Accumulated Depreciation | (6,858,800) | (6,722,400) |
| Net Plant | 21,641,898 | 21,350,510 |
| Emission Allowances | 361,779 | 328,721 |
| Public Service Company Of New Hampshire [Member] | ||
| Regulatory Assets [Line Items] | ||
| Gross Plant | 4,247,000 | 4,197,300 |
| Accumulated Depreciation | (1,277,700) | (1,254,700) |
| Net Plant | 3,076,608 | 3,039,313 |
| Emission Allowances | 165,725 | $ 162,354 |
| Electricity Generation Plant, Non-Nuclear [Member] | Public Service Company Of New Hampshire [Member] | ||
| Regulatory Assets [Line Items] | ||
| Gross Plant | 1,192,600 | |
| Accumulated Depreciation | (564,100) | |
| Net Plant | 628,500 | |
| Fuel | 98,300 | |
| Materials and Supplies | 48,500 | |
| Emission Allowances | 19,700 | |
| Total Generation Assets | $ 795,000 |