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Fair Value of Derivative and Other Financial Instruments - Recurring (Details) - USD ($) $ in Thousands | Sep. 30, 2015 | Dec. 31, 2014
--- | --- | ---
PNMR and PNM [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | $ 242,795 | $ 250,145
PNMR and PNM [Member] | Cash and equivalents [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 28,813 | 8,276
PNMR and PNM [Member] | Domestic value [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 42,769 | 45,340
PNMR and PNM [Member] | Domestic growth [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 58,424 | 74,053
PNMR and PNM [Member] | International and other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 1,681 | 16,599
PNMR and PNM [Member] | U.S. Government [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 25,544 | 22,563
PNMR and PNM [Member] | Municipals [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 61,106 | 68,973
PNMR and PNM [Member] | Corporate and other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 24,458 | 14,341
PNM Resources [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 2,297,887 | 2,173,117
Investment in PVNGS lessor notes | 8,947 | 32,836
Other investments | 1,142 | 2,375
PNM Resources [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Investment in PVNGS lessor notes | 0 | 0
Other investments | 490 | 639
PNM Resources [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 2,297,887 | 2,173,117
Investment in PVNGS lessor notes | 0 | 0
Other investments | 0 | 0
PNM Resources [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Investment in PVNGS lessor notes | 8,947 | 32,836
Other investments | 652 | 1,736
PNM Resources [Member] | Reported Value Measurement [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 2,105,381 | 1,975,090
Investment in PVNGS lessor notes | 8,824 | 31,232
Other investments | 490 | 1,762
Public Service Company of New Mexico [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 1,719,947 | 1,624,222
Investment in PVNGS lessor notes | 8,947 | 32,836
Other investments | 252 | 397
Public Service Company of New Mexico [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Investment in PVNGS lessor notes | 0 | 0
Other investments | 252 | 397
Public Service Company of New Mexico [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 1,719,947 | 1,624,222
Investment in PVNGS lessor notes | 0 | 0
Other investments | 0 | 0
Public Service Company of New Mexico [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Investment in PVNGS lessor notes | 8,947 | 32,836
Other investments | 0 | 0
Public Service Company of New Mexico [Member] | Reported Value Measurement [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 1,589,991 | 1,490,657
Investment in PVNGS lessor notes | 8,824 | 31,232
Other investments | 252 | 397
Texas-New Mexico Power Company [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 427,940 | 427,356
Other investments | 238 | 242
Texas-New Mexico Power Company [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Other investments | 238 | 242
Texas-New Mexico Power Company [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 427,940 | 427,356
Other investments | 0 | 0
Texas-New Mexico Power Company [Member] | Fair Value, Inputs, Level 3 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 0 | 0
Other investments | 0 | 0
Texas-New Mexico Power Company [Member] | Reported Value Measurement [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Long-term debt | 365,390 | 365,667
Other investments | 238 | 242
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 242,795 | 250,145
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 160,110 | 169,919
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 82,685 | 80,226
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Commodity Contract [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Commodity derivative assets | 9,513 | 11,232
Commodity derivative liabilities | (984) | (1,686)
Commodity derivative instruments, Net | 8,529 | 9,546
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Commodity Contract [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Commodity derivative assets | 0 | 0
Commodity derivative liabilities | 0 | 0
Commodity derivative instruments, Net | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Commodity Contract [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Commodity derivative assets | 9,513 | 11,232
Commodity derivative liabilities | (984) | (1,686)
Commodity derivative instruments, Net | 8,529 | 9,546
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Cash and equivalents [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 28,813 | 8,276
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Cash and equivalents [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 28,813 | 8,276
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Cash and equivalents [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic value [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 42,769 | 45,340
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic value [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 42,769 | 45,340
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic value [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic growth [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 58,424 | 74,053
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic growth [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 58,424 | 74,053
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Domestic growth [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | International and other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 1,681 | 16,599
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | International and other [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 1,681 | 16,599
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | International and other [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | U.S. Government [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 25,544 | 22,563
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | U.S. Government [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 24,254 | 20,808
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | U.S. Government [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 1,290 | 1,755
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Municipals [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 61,106 | 68,973
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Municipals [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 0 | 0
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Municipals [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 61,106 | 68,973
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Corporate and other [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 24,458 | 14,341
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Corporate and other [Member] | Fair Value, Inputs, Level 1 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | 4,169 | 4,843
Fair Value, Measurements, Recurring [Member] | PNMR and PNM [Member] | Corporate and other [Member] | Fair Value, Inputs, Level 2 [Member] |  |
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] |  |
Investments | $ 20,289 | $ 9,498

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