Pension and Other Postretirement Benefits - Schedule of Pre-Tax Information About Net Actuarial (Gain) Loss in AOCI (Details) $ in Thousands	12 Months Ended
Dec. 31, 2024 USD ($)
PNM \| Pension Plan
Net actuarial (gain) loss
Amounts in AOCI not yet recognized in net periodic benefit cost at beginning of year	$ 104,067
Experience (gain) loss	12,081
Regulatory asset (liability) adjustment	(8,853)
Amortization recognized in net periodic benefit (income)	(4,782)
Amounts in AOCI not yet recognized in net periodic benefit cost at end of year	102,513
PNM \| Executive Retirement Program
Net actuarial (gain) loss
Amounts in AOCI not yet recognized in net periodic benefit cost at beginning of year	1,104
Experience (gain) loss	(45)
Regulatory asset (liability) adjustment	26
Amortization recognized in net periodic benefit (income)	(84)
Amounts in AOCI not yet recognized in net periodic benefit cost at end of year	1,001
TNMP \| Pension Plan
Net actuarial (gain) loss
Amounts in AOCI not yet recognized in net periodic benefit cost at beginning of year	0
Experience (gain) loss	456
Regulatory asset (liability) adjustment	(456)
Amortization recognized in net periodic benefit (income)	0
Amounts in AOCI not yet recognized in net periodic benefit cost at end of year	0
TNMP \| Executive Retirement Program
Net actuarial (gain) loss
Amounts in AOCI not yet recognized in net periodic benefit cost at beginning of year	0
Experience (gain) loss	(314)
Regulatory asset (liability) adjustment	314
Amortization recognized in net periodic benefit (income)	0
Amounts in AOCI not yet recognized in net periodic benefit cost at end of year	$ 0

Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Actuarial (Gain) Loss, Regulatory Asset (Liability) Adjustment, before Tax

No definition available.

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- Definition

Amount, before tax, of accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-Publisher FASB
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- References

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- Definition

Amount, before tax, of gain (loss) for (increase) decrease in value of benefit obligation for change in actuarial assumptions and increase (decrease) in value of plan assets from experience different from that assumed of defined benefit plan, that has not been recognized in net periodic benefit (cost) credit.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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- Definition

Amount, before tax, of reclassification adjustment from accumulated other comprehensive income (loss) for gain (loss) of defined benefit plan.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Name Accounting Standards Codification
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-URI https://asc.fasb.org/1943274/2147482790/220-10-45-17A

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