XML 143 R110.htm IDEA: XBRL DOCUMENT v3.25.0.1
Pension and Other Postretirement Benefits - Narrative (Details) - USD ($)
 12 Months Ended
Jan. 01, 2018
Dec. 31, 2024
Dec. 31, 2023
Dec. 31, 2022
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected return on plan assets   4.00%    
Amortization of gains and losses that are outside the corridor   5 years    
Maximum annual contributions per employee (as a percent)   75.00%    
Employer matching contribution, percent of employees' gross pay (as a percent)   6.00%    
Minimum        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Non-matching contribution of eligible compensation based on eligible employee's age (as a percent)   3.00%    
Maximum        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Non-matching contribution of eligible compensation based on eligible employee's age (as a percent)   10.00%    
PNM        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Rate of return (as a percent)   3.33%    
TNMP        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Rate of return (as a percent)   0.62%    
Pension Plan        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected long-term return resulting from effect of 1% change   1.00%    
Expected long-term return resulting from effect of one-percentage point increase   1.00%    
Expected future employer contributions, year one through four   $ 0    
Expected future employer contributions, year five   $ 7,900,000    
Weighted average discount rate related to anticipated contributions (as a percent)   5.35%    
Pension Plan | Equity Securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   35.00%    
Pension Plan | Fixed Income        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   50.00%    
Pension Plan | Alternative Investments        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   15.00%    
Pension Plan | PNM        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected return on plan assets   6.86% 6.30% 5.50%
Expected long-term return on assets decrease resulting in increase net periodic costs In next fiscal year   $ 4,100,000    
Actuarial gains (losses) recorded as regulatory assets and liabilities   (12,081,000)    
Employer contributions   $ 1,000 $ 0  
Pension Plan | TNMP        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected return on plan assets   5.95% 5.50% 4.40%
Expected long-term return on assets decrease resulting in increase net periodic costs In next fiscal year   $ 400,000    
Actuarial gains (losses) recorded as regulatory assets and liabilities   (456,000)    
Employer contributions   $ 151,000 $ 0  
Pension Plan | TNMP | Equity Securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   16.00%    
Pension Plan | TNMP | Fixed Income        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   70.00%    
Pension Plan | TNMP | Alternative Investments        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   14.00%    
Other Postretirement Benefits        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected long-term return resulting from effect of 1% change   1.00%    
Other Postretirement Benefits | Equity Securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   30.00%    
Other Postretirement Benefits | Fixed Income        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   70.00%    
Other Postretirement Benefits | PNM        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected return on plan assets   6.60% 5.90% 4.75%
Expected long-term return on assets decrease resulting in increase net periodic costs In next fiscal year   $ 800,000    
Rate of return (as a percent)   4.50%    
Actuarial gains (losses) recorded as regulatory assets and liabilities   $ (100,000)    
Employer matching contribution, maximum 5.00%      
Employer contributions   193,000 $ 157,000  
Expected employer contributions in current fiscal year   $ 100,000 $ 0  
Other Postretirement Benefits | TNMP        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected return on plan assets   5.25% 4.70% 3.80%
Expected long-term return on assets decrease resulting in increase net periodic costs In next fiscal year   $ 100,000    
Rate of return (as a percent)   0.30%    
Actuarial gains (losses) recorded as regulatory assets and liabilities   $ (300,000)    
Effect of 1%-point change in assumed health care cost trend rates on net periodic expense and APBO   0    
Employer contributions   0 $ 0  
Expected employer contributions in current fiscal year   200,000 0  
Other Postretirement Benefits | PNM and TNMP        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Expected employer contributions in fiscal year through year 5   0    
Expected employer disbursements for next fiscal year   2,000,000.0    
Expected employer disbursements by employer in year 2 through year 5   11,100,000    
Executive Retirement Program | PNM        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Actuarial gains (losses) recorded as regulatory assets and liabilities   45,000    
Expected disbursements by employer   1,300,000 1,300,000  
Executive Retirement Program | TNMP        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Actuarial gains (losses) recorded as regulatory assets and liabilities   314,000    
Expected disbursements by employer   $ 100,000 $ 100,000  
Non-US | Pension Plan | Equity Securities        
Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items]        
Investment allocation targets (as a percent)   13.00%