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Pension and Other Postretirement Benefit Plans (Tables) | 3 Months Ended
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Mar. 31, 2016
Public Service Company of New Mexico [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Net Benefit Costs | The following tables present the components of the PNM Plans’ net periodic benefit cost:
| Three Months Ended March 31,
| Pension Plan |  | OPEB Plan |  | Executive Retirement Program
| 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015
| (In thousands)
Components of Net Periodic Benefit Cost |  |  |  |  |  |  |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | 35 |  |  | $ | 51 |  |  | $ | — |  |  | $ | — |
Interest cost | 7,577 |  |  | 7,064 |  |  | 1,087 |  |  | 1,022 |  |  | 203 |  |  | 190 |
Expected return on plan assets | (8,854 | ) |  | (9,831 | ) |  | (1,371 | ) |  | (1,403 | ) |  | — |  |  | — |
Amortization of net (gain) loss | 3,455 |  |  | 3,705 |  |  | 286 |  |  | 491 |  |  | 64 |  |  | 81 |
Amortization of prior service cost | (241 | ) |  | (241 | ) |  | (7 | ) |  | (160 | ) |  | — |  |  | — |
Net periodic benefit cost | $ | 1,937 |  |  | $ | 697 |  |  | $ | 30 |  |  | $ | 1 |  |  | $ | 267 |  |  | $ | 271 |
Texas-New Mexico Power Company [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Net Benefit Costs | The following tables present the components of the TNMP Plans’ net periodic benefit cost (income):
| Three Months Ended March 31,
| Pension Plan |  | OPEB Plan |  | Executive Retirement Program
| 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015
| (In thousands)
Components of Net Periodic Benefit Cost (Income) |  |  |  |  |  |  |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | 46 |  |  | $ | 62 |  |  | $ | — |  |  | $ | — |
Interest cost | 826 |  |  | 761 |  |  | 169 |  |  | 152 |  |  | 10 |  |  | 9 |
Expected return on plan assets | (986 | ) |  | (1,105 | ) |  | (122 | ) |  | (130 | ) |  | — |  |  | — |
Amortization of net (gain) loss | 175 |  |  | 195 |  |  | (10 | ) |  | — |  |  | 1 |  |  | 1 |
Amortization of prior service cost | — |  |  | — |  |  | — |  |  | — |  |  | — |  |  | — |
Net Periodic Benefit Cost (Income) | $ | 15 |  |  | $ | (149 | ) |  | $ | 83 |  |  | $ | 84 |  |  | $ | 11 |  |  | $ | 10 |

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- Definition Tabular disclosure of the components of net benefit costs for pension plans and/or other employee benefit plans including service cost, interest cost, expected return on plan assets, gain (loss), prior service cost or credit, transition asset or obligation, and gain (loss) recognized due to settlements or curtailments. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 1 -Subparagraph (h) -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e1928-114920 + Details
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