XML 78 R56.htm IDEA: XBRL DOCUMENT v3.21.1
Pension and Other Postretirement Benefit Plans (Details) - USD ($)
 3 Months Ended
Mar. 31, 2021
Mar. 31, 2020
PNM | Pension Plan    
Components of Net Periodic Benefit Cost    
Service cost $ 0 $ 0
Interest cost 4,036,000 4,985,000
Expected return on plan assets (7,133,000) (7,363,000)
Amortization of net loss 4,541,000 4,465,000
Amortization of prior service cost 0 (138,000)
Net Periodic Benefit Cost (Income) 1,444,000 1,949,000
Contributions by employer 0 0
Expected employer contributions, remainder of fiscal year 0  
Expected employer contributions in year 2 10,800,000  
Expected employer contributions in year 3 11,500,000  
Expected employer contributions in year 4 $ 10,600,000  
PNM | Pension Plan | Maximum    
Components of Net Periodic Benefit Cost    
Assumptions used calculating net periodic benefit cost, discount rate 2.90%  
PNM | OPEB Plan    
Components of Net Periodic Benefit Cost    
Service cost $ 6,000 10,000
Interest cost 477,000 613,000
Expected return on plan assets (1,042,000) (1,387,000)
Amortization of net loss 0 87,000
Amortization of prior service cost 0 0
Net Periodic Benefit Cost (Income) (559,000) (677,000)
Contributions by employer 0 0
Disbursements by employer 900,000 1,100,000
Expected employer disbursements for remainder of fiscal year 3,300,000  
Expected employer disbursements in year 2 through 5 13,100,000  
PNM | Executive Retirement Program    
Components of Net Periodic Benefit Cost    
Service cost 0 0
Interest cost 90,000 122,000
Expected return on plan assets 0 0
Amortization of net loss 100,000 101,000
Amortization of prior service cost 0 0
Net Periodic Benefit Cost (Income) 190,000 223,000
Disbursements by employer 400,000 300,000
Expected employer disbursements for remainder of fiscal year 1,300,000  
Expected employer disbursements in year 2 through 5 4,900,000  
TNMP | Pension Plan    
Components of Net Periodic Benefit Cost    
Service cost 0 0
Interest cost 435,000 544,000
Expected return on plan assets (795,000) (821,000)
Amortization of net loss 312,000 315,000
Amortization of prior service cost 0 0
Net Periodic Benefit Cost (Income) (48,000) 38,000
Contributions by employer 0 0
Estimated employer contributions remainder of fiscal year through year two $ 0  
TNMP | Pension Plan | Maximum    
Components of Net Periodic Benefit Cost    
Assumptions used calculating net periodic benefit cost, discount rate 2.90%  
TNMP | OPEB Plan    
Components of Net Periodic Benefit Cost    
Service cost $ 11,000 12,000
Interest cost 77,000 93,000
Expected return on plan assets (102,000) (134,000)
Amortization of net loss (80,000) (81,000)
Amortization of prior service cost 0 0
Net Periodic Benefit Cost (Income) (94,000) (110,000)
Contributions by employer 0 0
Estimated employer contributions for remainder of fiscal year through year 5 0  
TNMP | Executive Retirement Program    
Components of Net Periodic Benefit Cost    
Service cost 0 0
Interest cost 4,000 6,000
Expected return on plan assets 0 0
Amortization of net loss 9,000 6,000
Amortization of prior service cost 0 0
Net Periodic Benefit Cost (Income) 13,000 12,000
Expected employer disbursements for remainder of fiscal year 100,000  
Expected employer disbursements in year 2 through 5 300,000  
TNMP | Executive Retirement Program | Maximum    
Components of Net Periodic Benefit Cost    
Disbursements by employer $ 0 $ 0