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Financing - Schedule of maturities and interest rates (Details) - Public Service Company of New Mexico - Senior Unsecured Notes | Jul. 28, 2017 USD ($)
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SUNs, Issuance in May 2018, Interest rate of 3.15% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 55,000,000.0
Stated percentage | 3.15%
Senior SUNs, Issuance in May 2018, Interest rate of 3.45% Note Agreement (SUNs), Private Placement Transaction with Institutional Investors, Issuance in May 2018, Interest Rate of 3.45% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 104,000,000
Stated percentage | 3.45%
SUNs, Issuance in May 2018, Interest rate of 3.69% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 88,000,000
Stated percentage | 3.68%
SUNs, Issuance in May 2018, Interest rate of 3.93% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 38,000,000
Stated percentage | 3.93%
SUNs, Issuance in May 2018, Interest rate of 4.22% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 45,000,000
Stated percentage | 4.22%
SUNs, Issuance in May 2018, Interest rate of 4.50% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 20,000,000
Stated percentage | 4.50%
SUNs, Issuance in August 2018, Interest rate of 3.78% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 15,000,000
Stated percentage | 3.78%
SUNs, Issuance in August 2018, Interest rate of 4.60% |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 85,000,000
Stated percentage | 4.60%
Senior Unsecured Note Agreement (SUNs) |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 450,000,000.0
Scenario, plan | SUNs, Issuance in May 2018 |
Debt Instrument [Line Items] |
Aggregate principal amount | 350,000,000.0
Scenario, plan | SUN's, Issuance in August 2018 |
Debt Instrument [Line Items] |
Aggregate principal amount | $ 100,000,000

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