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Regulatory and Rate Matters - TNMP Narrative (Details) - Texas-New Mexico Power Company |  | 1 Months Ended | 3 Months Ended |  |
--- | --- | --- | --- | --- | ---
Mar. 13, 2017 USD ($) | Jul. 30, 2011 USD ($) | Mar. 31, 2017 USD ($) customer | Apr. 24, 2017 customer | Dec. 31, 2016 advanced_meter
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Adjustment of the most recent annual CTC funding amount (greater than or equal to) |  |  | 15.00% |  |
Requested increase (decrease) adjustment to reduce collection of amortization | $ (1,100,000) |  |  |  |
Advanced Meter System Deployment and Surcharge Request |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved deployment costs |  | $ 113,400,000 |  |  |
Collection of deployment costs through surcharge period |  | 12 years |  |  |
Number of advanced meters installed | advanced_meter |  |  |  |  | 242,000
Recovery in cost through initial fees |  |  | $ 200,000 |  |
Ongoing annual expenses |  |  | 500,000 |  |
Approved non-standard metering ongoing expenses monthly charge |  |  | $ 36.78 |  |
Presumed number of customers that will elect non-standard meter service (in customers) | customer |  |  | 1,081 |  |
Advanced Meter System Deployment and Surcharge Request | Subsequent event |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Current number of customers that have elected non-standard meter service (in customers) | customer |  |  |  | 103 |
Advanced Meter System Deployment and Surcharge Request | Minimum |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved non-standard metering service cost, initial fee range |  |  | $ 63.97 |  |
Advanced Meter System Deployment and Surcharge Request | Maximum |  |  |  |  |
Public Utilities, General Disclosures [Line Items] |  |  |  |  |
Approved non-standard metering service cost, initial fee range |  |  | $ 168.61 |  |

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