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Pension and Other Postretirement Benefit Plans (Tables) | 12 Months Ended
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Dec. 31, 2011
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Defined Benefit Plans Disclosures [Table Text Block] | The fair values of investments held by the employee benefit plans are as follows:
| Total |  | Quoted Prices in Active Market for Identical Assets (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
December 31, 2011 |  |  | (In thousands) |  |
PNM Pension Plan |  |  |  |  |  |  |
Participation in PNMR Master Trust Total Plan Investments | $ | 444,466 |  |  | $ | 176,279 |  |  | $ | 184,054 |  |  | $ | 84,133 |
TNMP Pension Plan |  |  |  |  |  |  |
Participation in PNMR Master Trust Total Plan Investments | $ | 62,139 |  |  | $ | 24,118 |  |  | $ | 23,466 |  |  | $ | 14,555 |
PNM OPEB Plan |  |  |  |  |  |  |
Cash and equivalents | $ | 1,128 |  |  | $ | 1,128 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International funds | 2,740 |  |  | — |  |  | 2,740 |  |  | — |
Domestic value | 1,289 |  |  | 1,289 |  |  | — |  |  | — |
Domestic growth | 43,016 |  |  | 22,215 |  |  | 20,801 |  |  | — |
Other funds | 7,678 |  |  | — |  |  | 7,678 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Mutual funds | 4,006 |  |  | 4,006 |  |  | — |  |  | — |
Total Assets | $ | 59,857 |  |  | $ | 28,638 |  |  | $ | 31,219 |  |  | $ | — |
TNMP OPEB Plan |  |  |  |  |  |  |
Cash and equivalents | $ | 180 |  |  | $ | 180 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International funds | 1,248 |  |  | — |  |  | 1,248 |  |  | — |
Domestic value | 551 |  |  | 551 |  |  | — |  |  | — |
Domestic growth | 738 |  |  | 738 |  |  | — |  |  | — |
Other funds | 3,048 |  |  | — |  |  | 3,048 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Mutual funds | 2,694 |  |  | 2,694 |  |  | — |  |  | — |
Total Assets | $ | 8,459 |  |  | $ | 4,163 |  |  | $ | 4,296 |  |  | $ | — |
| Total |  | Quoted Prices in Active Market for Identical Assets (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
December 31, 2010 | (In thousands)
PNM Pension Plan |  |  |  |  |  |  |
Participation in PNMR Master Trust | $ | 393,480 |  |  | $ | 208,759 |  |  | $ | 105,781 |  |  | $ | 78,940 |
TNMP Pension Plan |  |  |  |  |  |  |
Participation in PNMR Master Trust | $ | 60,506 |  |  | $ | 30,530 |  |  | $ | 16,317 |  |  | $ | 13,659 |
PNM OPEB Plan |  |  |  |  |  |  |
Cash and equivalents | $ | 1,811 |  |  | $ | 1,811 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International funds | 3,182 |  |  | — |  |  | 3,182 |  |  | — |
Domestic value | 1,363 |  |  | 1,363 |  |  | — |  |  | — |
Domestic growth | 41,278 |  |  | 22,939 |  |  | 18,339 |  |  | — |
Other funds | 9,057 |  |  | — |  |  | 9,057 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Mutual funds | 5,860 |  |  | 5,860 |  |  | — |  |  | — |
Total Assets | $ | 62,551 |  |  | $ | 31,973 |  |  | $ | 30,578 |  |  | $ | — |
TNMP OPEB Plan |  |  |  |  |  |  |
Cash and equivalents | $ | 424 |  |  | $ | 424 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International funds | 1,116 |  |  | — |  |  | 1,116 |  |  | — |
Domestic value | 582 |  |  | 582 |  |  | — |  |  | — |
Domestic growth | 710 |  |  | 710 |  |  | — |  |  | — |
Other funds | 2,959 |  |  | — |  |  | 2,959 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Mutual funds | 2,834 |  |  | 2,834 |  |  | — |  |  | — |
Total Assets | $ | 8,625 |  |  | $ | 4,550 |  |  | $ | 4,075 |  |  | $ | — |
The fair values of investments in the PNMR Master Trust are as follows:
| Total |  | Quoted Prices in Active Market for Identical Assets (Level 1) |  | Significant Other Observable Inputs (Level 2) |  | Significant Unobservable Inputs (Level 3)
December 31, 2011 | (In thousands)
PNMR Master Trust |  |  |  |  |  |  |
Cash and equivalents | $ | 6,753 |  |  | $ | 6,753 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International | 37,173 |  |  | 37,173 |  |  | — |  |  | — |
Domestic value | 58,350 |  |  | 57,437 |  |  | 913 |  |  | — |
Domestic growth | 65,004 |  |  | 65,004 |  |  | — |  |  | — |
Other funds | 15,271 |  |  | — |  |  | 15,271 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Corporate | 59,730 |  |  | — |  |  | 59,730 |  |  | — |
U.S. government | 104,102 |  |  | 34,030 |  |  | 70,072 |  |  | — |
Municipals | 3,478 |  |  | — |  |  | 3,478 |  |  | — |
Other funds | 58,056 |  |  | — |  |  | 58,056 |  |  | — |
Alternative investments: |  |  |  |  |  |  |
Private equity funds | 37,100 |  |  | — |  |  | — |  |  | 37,100 |
Hedge funds | 36,904 |  |  | — |  |  | — |  |  | 36,904 |
Real estate funds | 24,684 |  |  | — |  |  | — |  |  | 24,684 |
Total Fair Value of Plan Investments | $ | 506,605 |  |  | $ | 200,397 |  |  | $ | 207,520 |  |  | $ | 98,688 |
December 31, 2010 |
PNMR Master Trust |  |  |  |  |  |  |
Cash and equivalents | $ | 10,718 |  |  | $ | 10,718 |  |  | $ | — |  |  | $ | — |
Equity securities: |  |  |  |  |  |  |
International | 46,505 |  |  | 46,505 |  |  | — |  |  | — |
Domestic value | 79,218 |  |  | 76,493 |  |  | 2,725 |  |  | — |
Domestic growth | 81,375 |  |  | 81,375 |  |  | — |  |  | — |
Other funds | 49,307 |  |  | — |  |  | 49,307 |  |  | — |
Fixed income securities: |  |  |  |  |  |  |
Corporate | 2,062 |  |  | — |  |  | 2,062 |  |  | — |
U.S. government | 39,585 |  |  | 24,198 |  |  | 15,387 |  |  | — |
Municipals | 2,935 |  |  | — |  |  | 2,935 |  |  | — |
Other funds | 49,682 |  |  | — |  |  | 49,682 |  |  | — |
Alternative investments: |  |  |  |  |  |  |
Private equity funds | 32,935 |  |  | — |  |  | — |  |  | 32,935 |
Hedge funds | 37,622 |  |  | — |  |  | — |  |  | 37,622 |
Real estate funds | 22,042 |  |  | — |  |  | — |  |  | 22,042 |
Total Assets | $ | 453,986 |  |  | $ | 239,289 |  |  | $ | 122,098 |  |  | $ | 92,599 |
A reconciliation of the changes in Level 3 fair value measurements is as follows:
| Year Ended December 31,
Level 3 Fair Value Assets and Liabilities | 2011 |  | 2010
| (In thousands)
PNM Pension | Master Trust |  | Master Trust |  | Real Estate Funds
Balance at beginning of period | $ | 78,940 |  |  | $ | 74,105 |  |  | $ | 2,168 |
Actual return on assets sold during the period | 1,624 |  |  | (778 | ) |  | (1,846 | )
Actual return on assets still held at period end | 1,404 |  |  | 4,015 |  |  | — |
Purchases | 4,030 |  |  | 33,731 |  |  | — |
Sales | (1,865 | ) |  | (32,133 | ) |  | (322 | )
Balance at end of period | $ | 84,133 |  |  | $ | 78,940 |  |  | $ | — |
TNMP Pension |  |  |  |  |
Balance at beginning of period | $ | 13,659 |  |  | $ | 12,426 |  |  |
Actual return on assets sold during the period | 280 |  |  | (199 | ) |  |
Actual return on assets still held at period end | 243 |  |  | 1,024 |  |  |
Purchases | 695 |  |  | 8,602 |  |  |
Sales | (322 | ) |  | (8,194 | ) |  |
Balance at end of period | $ | 14,555 |  |  | $ | 13,659 |  |  |  |
Additional information concerning changes in Level 3 fair value measurements for the PNMR Master Trust is as follows: Level 3 Fair Value Assets and Liabilities
PNMR Master Trust | Private equity funds |  | Hedge funds |  | Real estate funds |  | Total
|  |  | (In thousands) |  |
Balance at December 31, 2009 | $ | 26,883 |  |  | $ | 34,921 |  |  | $ | 24,727 |  |  | $ | 86,531 |
Actual return on assets sold during the period | (769 | ) |  | — |  |  | (208 | ) |  | (977 | )
Actual return on assets still held at period end | 2,363 |  |  | 2,701 |  |  | (25 | ) |  | 5,039 |
Purchases | 39,255 |  |  | — |  |  | 3,078 |  |  | 42,333 |
Sales | (34,797 | ) |  | — |  |  | (5,530 | ) |  | (40,327 | )
Balance at December 31, 2010 | 32,935 |  |  | 37,622 |  |  | 22,042 |  |  | 92,599 |
Actual return on assets sold during the period | 1,904 |  |  | — |  |  | — |  |  | 1,904 |
Actual return on assets still held at period end | 2,372 |  |  | (718 | ) |  | (7 | ) |  | 1,647 |
Purchases | 2,076 |  |  | — |  |  | 2,649 |  |  | 4,725 |
Sales | (2,187 | ) |  | — |  |  | — |  |  | (2,187 | )
Balance at December 31, 2011 | $ | 37,100 |  |  | $ | 36,904 |  |  | $ | 24,684 |  |  | $ | 98,688 |
Schedule of Defined Contribution Plan Expenses [Table Text Block] | A summary of expenses for these other retirement plans is as follows:
| Year Ended December 31,
| 2011 |  | 2010 |  | 2009
| (In thousands)
PNMR |  |  |  |  |
401(k) plan | $ | 17,000 |  |  | $ | 17,199 |  |  | $ | 16,743 |
Non-qualified plan | $ | 1,931 |  |  | $ | 2,500 |  |  | $ | 2,073 |
PNM |  |  |  |  |
401(k) plan | $ | 12,541 |  |  | $ | 12,788 |  |  | $ | 11,698 |
Non-qualified plan | $ | 1,407 |  |  | $ | 1,871 |  |  | $ | 1,299 |
TNMP |  |  |  |  |
401(k) plan | $ | 3,723 |  |  | $ | 3,496 |  |  | $ | 3,323 |
Non-qualified plan | $ | 431 |  |  | $ | 478 |  |  | $ | 405 |
Pension Plan [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Defined Benefit Plans Disclosures [Table Text Block] | The following table presents information about the PBO, fair value of plan assets, and funded status of the plans:
| PNM Plan |  | TNMP Plan
| Year Ended December 31, |  | Year Ended December 31,
| 2011 |  | 2010 |  | 2011 |  | 2010
| (In thousands)
PBO at beginning of year | $ | 593,457 |  |  | $ | 545,747 |  |  | $ | 72,260 |  |  | $ | 68,636 |
Service cost | — |  |  | — |  |  | — |  |  | — |
Interest cost | 32,804 |  |  | 34,073 |  |  | 3,800 |  |  | 4,126 |
Actuarial (gain) loss | 1,197 |  |  | 51,379 |  |  | (2,793 | ) |  | 5,113 |
Benefits paid | (38,584 | ) |  | (37,742 | ) |  | (6,033 | ) |  | (5,615 | )
PBO at end of year | 588,874 |  |  | 593,457 |  |  | 67,234 |  |  | 72,260 |
Fair value of plan assets at beginning of year | 392,788 |  |  | 360,854 |  |  | 60,387 |  |  | 57,744 |
Actual return on plan assets | 31,671 |  |  | 51,725 |  |  | 4,447 |  |  | 8,013 |
Employer contributions | 41,511 |  |  | 17,951 |  |  | 1,151 |  |  | 245 |
Benefits paid | (38,584 | ) |  | (37,742 | ) |  | (6,033 | ) |  | (5,615 | )
Fair value of plan assets at end of year | 427,386 |  |  | 392,788 |  |  | 59,952 |  |  | 60,387 |
Funded status-asset (liability) for pension benefits | $ | (161,488 | ) |  | $ | (200,669 | ) |  | $ | (7,282 | ) |  | $ | (11,873 | )
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block] | The following table presents pre-tax information about prior service cost and net actuarial (gain) loss in AOCI as of December 31, 2011.
| PNM Plan |  | TNMP Plan
| December 31, 2011 |  | December 31, 2011
| Prior service cost |  | Net actuarial (gain) loss |  | Net actuarial (gain) loss
| (In thousands)
Amounts in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year | $ | 314 |  |  | $ | 133,153 |  |  | $ | 521 |
Experience loss (gain) | — |  |  | 6,601 |  |  | (1,863 | )
Regulatory asset (liability) adjustment | (3 | ) |  | (1,592 | ) |  | 1,358 |
Amortization recognized in net periodic benefit cost (income) | (140 | ) |  | (4,074 | ) |  | (16 | )
Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year | $ | 171 |  |  | $ | 134,088 |  |  | $ | — |
Amortization expected to be recognized in 2012 | $ | (138 | ) |  | $ | (4,573 | ) |  | $ | — |
Schedule of Net Benefit Costs [Table Text Block] | The following table presents the components of net periodic benefit cost (income) recognized in the Consolidated Statements of Earnings (Loss):
| Year Ended December 31,
| 2011 |  | 2010 |  | 2009
| (In thousands)
PNM Plan |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | — |
Interest cost | 32,804 |  |  | 34,073 |  |  | 34,439 |
Expected return on plan assets | (37,075 | ) |  | (37,354 | ) |  | (38,763 | )
Amortization of net (gain) loss | 9,209 |  |  | 6,450 |  |  | 3,818 |
Amortization of prior service cost | 317 |  |  | 317 |  |  | 317 |
Net periodic benefit cost (income) | $ | 5,255 |  |  | $ | 3,486 |  |  | $ | (189 | )
TNMP Plan |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | — |
Interest cost | 3,800 |  |  | 4,126 |  |  | 4,396 |
Expected return on plan assets | (5,470 | ) |  | (5,794 | ) |  | (6,093 | )
Amortization of net (gain) loss | 346 |  |  | — |  |  | — |
Amortization of prior service cost | — |  |  | — |  |  | — |
Net periodic benefit cost (income) | $ | (1,324 | ) |  | $ | (1,668 | ) |  | $ | (1,697 | )
Schedule of Assumptions Used [Table Text Block] | The following significant weighted-average assumptions were used to determine the PBO and net periodic benefit cost (income). Should actual experience differ from actuarial assumptions, the PBO and net periodic benefit cost (income) would be affected.
| Year Ended December 31,
PNM Plan | 2011 |  | 2010 |  | 2009
Discount rate for determining December 31 PBO | 5.67 | % |  | 5.72 | % |  | 6.47 | %
Discount rate for determining net periodic benefit cost (income) | 5.72 | % |  | 6.47 | % |  | 7.25 | %
Expected return on plan assets | 8.50 | % |  | 8.75 | % |  | 8.75 | %
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
TNMP Plan |  |  |  |  |
Discount rate for determining December 31 PBO | 5.69 | % |  | 5.50 | % |  | 6.31 | %
Discount rate for determining net periodic benefit cost (income) | 5.50 | % |  | 6.31 | % |  | 7.25 | %
Expected return on plan assets | 8.50 | % |  | 8.75 | % |  | 8.75 | %
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
Schedule of Expected Benefit Payments [Table Text Block] | The following pension benefit payments are expected to be paid:
| PNM Plan |  | TNMP Plan
| (In thousands)
2012 | $ | 40,809 |  |  | $ | 6,690 |
2013 | 41,759 |  |  | 5,806 |
2014 | 42,536 |  |  | 6,236 |
2015 | 43,183 |  |  | 6,046 |
2016 | 43,715 |  |  | 5,690 |
Years 2017 – 2021 | 222,072 |  |  | 25,715 |
Other Postretirement Benefits [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Defined Benefit Plans Disclosures [Table Text Block] | The following table presents information about the APBO, the fair value of plan assets, and the funded status of the plans:
| PNM Plan |  | TNMP Plan
| Year Ended December 31, |  | Year Ended December 31,
| 2011 |  | 2010 |  | 2011 |  | 2010
| (In thousands)
APBO at beginning of year | $ | 99,486 |  |  | $ | 122,417 |  |  | $ | 12,152 |  |  | $ | 11,554 |
Service cost | 259 |  |  | 419 |  |  | 306 |  |  | 289 |
Interest cost | 5,378 |  |  | 7,650 |  |  | 654 |  |  | 711 |
Participant contributions | 2,206 |  |  | 1,732 |  |  | 281 |  |  | 257 |
Actuarial (gain) loss | 712 |  |  | (17,952 | ) |  | (862 | ) |  | (116 | )
Benefits paid | (10,315 | ) |  | (9,331 | ) |  | (1,187 | ) |  | (543 | )
Plan amendments | (1,505 | ) |  | (5,449 | ) |  | — |  |  | — |
APBO at end of year | 96,221 |  |  | 99,486 |  |  | 11,344 |  |  | 12,152 |
Fair value of plan assets at beginning of year | 61,749 |  |  | 57,126 |  |  | 8,596 |  |  | 7,093 |
Actual return on plan assets | 2,263 |  |  | 9,771 |  |  | 262 |  |  | 1,214 |
Employer contributions | 2,873 |  |  | 2,451 |  |  | 351 |  |  | 575 |
Participant contributions | 2,206 |  |  | 1,732 |  |  | 281 |  |  | 257 |
Benefits paid | (10,315 | ) |  | (9,331 | ) |  | (1,187 | ) |  | (543 | )
Fair value of plan assets at end of year | 58,776 |  |  | 61,749 |  |  | 8,303 |  |  | 8,596 |
Funded status-asset (liability) | $ | (37,445 | ) |  | $ | (37,737 | ) |  | $ | (3,041 | ) |  | $ | (3,556 | )
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block] | The following table presents pre-tax information about prior service cost and net actuarial (gain) loss in AOCI as of December 31, 2011.
| PNM Plan |  | TNMP Plan
| December 31, 2011 |  | December 31, 2011
| Prior service cost (credit) |  | Net actuarial (gain) loss |  | Prior service cost |  | Net actuarial (gain) loss
| (In thousands)
Amount in AOCI not yet recognized in net periodic benefit cost (income) at beginning of year | $ | (882 | ) |  | $ | 3,187 |  |  | $ | 12 |  |  | $ | (110 | )
Experience loss (gain) | (1,505 | ) |  | 3,837 |  |  | — |  |  | (431 | )
Regulatory asset (liability) adjustment | 2,164 |  |  | (5,940 | ) |  | (11 | ) |  | 537 |
Amortization recognized in net periodic benefit cost (income) | 102 |  |  | (124 | ) |  | (1 | ) |  | 4 |
Amounts in AOCI not yet recognized in net periodic benefit cost (income) at end of year | $ | (121 | ) |  | $ | 960 |  |  | $ | — |  |  | $ | — |
Amortization expected to be recognized in 2012 | $ | 35 |  |  | $ | (100 | ) |  | $ | — |  |  | $ | — |
Schedule of Net Benefit Costs [Table Text Block] | The following table presents the components of net periodic benefit cost recognized in the Consolidated Statements of Earnings (Loss):
| Year Ended December 31,
| 2011 |  | 2010 |  | 2009
| (In thousands)
PNM Plan |  |  |  |  |
Service cost | $ | 259 |  |  | $ | 419 |  |  | $ | 417 |
Interest cost | 5,378 |  |  | 7,650 |  |  | 7,388 |
Expected return on plan assets | (5,388 | ) |  | (5,572 | ) |  | (5,832 | )
Amortization of net (gain) loss | 3,205 |  |  | 5,489 |  |  | 3,290 |
Amortization of prior service credit | (2,648 | ) |  | (4,143 | ) |  | (4,262 | )
Net periodic benefit cost | $ | 806 |  |  | $ | 3,843 |  |  | $ | 1,001 |
TNMP Plan |  |  |  |  |
Service cost | $ | 306 |  |  | $ | 289 |  |  | $ | 260 |
Interest cost | 654 |  |  | 711 |  |  | 733 |
Expected return on plan assets | (533 | ) |  | (514 | ) |  | (495 | )
Amortization of net (gain) loss | (193 | ) |  | (195 | ) |  | (265 | )
Amortization of prior service cost | 60 |  |  | 60 |  |  | 60 |
Net periodic benefit cost | $ | 294 |  |  | $ | 351 |  |  | $ | 293 |
Schedule of Assumptions Used [Table Text Block] | The following significant weighted-average assumptions were used to determine the APBO and net periodic benefit cost. Should actual experience differ from actuarial assumptions, the APBO and net periodic benefit cost would be affected.
| Year Ended December 31,
PNM Plan | 2011 |  | 2010 |  | 2009
Discount rate for determining December 31 APBO | 5.70 | % |  | 5.59 | % |  | 6.42 | %
Discount rate for determining net periodic benefit cost | 5.59 | % |  | 6.42 | % |  | 7.25 | %
Expected return on plan assets | 8.50 | % |  | 8.75 | % |  | 8.75 | %
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
TNMP Plan |  |  |  |  |
Discount rate for determining December 31 APBO | 5.70 | % |  | 5.59 | % |  | 6.42 | %
Discount rate for determining net periodic benefit cost | 5.59 | % |  | 6.42 | % |  | 7.25 | %
Expected return on plan assets | 6.30 | % |  | 6.70 | % |  | 6.70 | %
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
Schedule of Expected Benefit Payments [Table Text Block] | The following other postretirement benefit payments, which reflect expected future service, are expected to be paid:
| PNM Plan |  | TNMP Plan
| (In thousands)
2012 | $ | 6,708 |  |  | $ | 777 |
2013 | 6,874 |  |  | 780 |
2014 | 7,138 |  |  | 797 |
2015 | 7,270 |  |  | 799 |
2016 | 7,520 |  |  | 816 |
Years 2017 – 2021 | 38,933 |  |  | 4,157 |
Schedule of Health Care Cost Trend Rates [Table Text Block] | The following table shows the assumed health care cost trend rates:
| PNM Plan
| December 31,
| 2011 |  | 2010
Health care cost trend rate assumed for next year | 7.5 | % |  | 8.0 | %
Rate to which the cost trend rate is assumed to decline (the ultimate trend rate) | 5.0 | % |  | 5.0 | %
Year that the rate reaches the ultimate trend rate | 2017 |  |  | 2017 |
Schedule of Effect of One-Percentage-Point Change in Assumed Health Care Cost Trend Rates [Table Text Block] | The following table shows the impact of a one-percentage-point change in assumed health care cost trend rates:
| PNM Plan
| 1-Percentage- Point Increase |  | 1-Percentage- Point Decrease
| (In thousands)
Effect on total of service and interest cost | $ | 424 |  |  | $ | (365 | )
Effect on APBO | $ | 6,215 |  |  | $ | (5,417 | )
Executive Retirement Program [Member] |
Defined Benefit Plan Disclosure [Line Items] |
Schedule of Amounts in Accumulated Other Comprehensive Income (Loss) to be Recognized over Next Fiscal Year [Table Text Block] | The following table presents pre-tax information about net actuarial loss in AOCI as of December 31, 2011.
| December 31, 2011
| PNM Plan |  | TNMP Plan
| (In thousands)
Amount in AOCI not yet recognized in net periodic benefit cost at beginning of year | $ | 1,588 |  |  | $ | — |
Experience loss (gain) | (252 | ) |  | 8 |
Regulatory asset (liability) adjustment | 59 |  |  | (8 | )
Amortization recognized in net periodic benefit cost (income) | (41 | ) |  | — |
Amount in AOCI not yet recognized in net periodic benefit cost at end of year | $ | 1,354 |  |  | $ | — |
Amortization expected to be recognized in 2012 | $ | (36 | ) |  | $ | — |
Schedule of Net Benefit Costs [Table Text Block] | The following table presents the components of net periodic benefit cost recognized in the Consolidated Statements of Earnings (Loss):
| Year Ended December 31,
| 2011 |  | 2010 |  | 2009
| (In thousands)
PNM Plan |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | 59 |
Interest cost | 930 |  |  | 1,053 |  |  | 1,135 |
Amortization of net loss | 93 |  |  | 71 |  |  | 27 |
Amortization of prior service cost | — |  |  | — |  |  | 10 |
Net periodic benefit cost | $ | 1,023 |  |  | $ | 1,124 |  |  | $ | 1,231 |
TNMP Plan |  |  |  |  |
Service cost | $ | — |  |  | $ | — |  |  | $ | — |
Interest cost | 46 |  |  | 52 |  |  | 76 |
Amortization of net (gain) loss | — |  |  | (4 | ) |  | — |
Amortization of prior service cost | — |  |  | — |  |  | — |
Net periodic benefit cost | $ | 46 |  |  | $ | 48 |  |  | $ | 76 |
Schedule of Assumptions Used [Table Text Block] | The following significant weighted-average assumptions were used to determine the PBO and net periodic benefit cost. Should actual experience differ from actuarial assumptions, the PBO and net periodic benefit cost would be affected.
| Year Ended December 31,
PNM Plan | 2011 |  | 2010 |  | 2009
Discount rate for determining December 31 PBO | 5.67 | % |  | 5.72 | % |  | 6.47 | %
Discount rate for determining net periodic benefit cost | 5.72 | % |  | 6.47 | % |  | 7.25 | %
Long-term rate of return on plan assets | N/A |  |  | N/A |  |  | N/A |
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
TNMP Plan |  |  |  |  |
Discount rate for determining December 31 PBO | 5.69 | % |  | 5.50 | % |  | 6.31 | %
Discount rate for determining net periodic benefit cost | 5.50 | % |  | 6.31 | % |  | 7.25 | %
Long-term rate of return on plan assets | N/A |  |  | N/A |  |  | N/A |
Rate of compensation increase | N/A |  |  | N/A |  |  | N/A |
Schedule of Expected Benefit Payments [Table Text Block] | The following executive retirement plan payments, which reflect expected future service, are expected:
| PNM Plan |  | TNMP Plan
| (In thousands)
2012 | $ | 1,477 |  |  | $ | 91 |
2013 | 1,460 |  |  | 90 |
2014 | 1,441 |  |  | 89 |
2015 | 1,418 |  |  | 87 |
2016 | 1,393 |  |  | 85 |
Years 2017 – 2021 | 6,462 |  |  | 375 |
Schedule of Net Funded Status [Table Text Block] | For the executive retirement programs, the following table presents information about the PBO and funded status of the plans:
| PNM Plan |  | TNMP Plan
| Year Ended December 31, |  | Year Ended December 31,
| 2011 |  | 2010 |  | 2011 |  | 2010
| (In thousands)
PBO at beginning of year | $ | 17,020 |  |  | $ | 17,004 |  |  | $ | 884 |  |  | $ | 867 |
Service cost | — |  |  | — |  |  | — |  |  | — |
Interest cost | 930 |  |  | 1,054 |  |  | 46 |  |  | 52 |
Actuarial (gain) loss | (252 | ) |  | 473 |  |  | 8 |  |  | 59 |
Benefits paid | (1,507 | ) |  | (1,511 | ) |  | (94 | ) |  | (94 | )
PBO at end of year-funded status | 16,191 |  |  | 17,020 |  |  | 844 |  |  | 884 |
Less current liability | 1,436 |  |  | 1,478 |  |  | 89 |  |  | 89 |
Non-current liability | $ | 14,755 |  |  | $ | 15,542 |  |  | $ | 755 |  |  | $ | 795 |

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