Lease Commitments - Schedule of Weighted Average Remaining Lease Terms and Discount Rates (Details)	Sep. 30, 2022
Weighted average remaining lease term (years):
Operating leases	6 years 8 months 8 days
Financing leases	3 years 8 months 26 days
Weighted average discount rate:
Operating leases	4.01%
Financing leases	3.08%
PNM
Weighted average remaining lease term (years):
Operating leases	6 years 11 months 23 days
Financing leases	4 years 3 days
Weighted average discount rate:
Operating leases	4.01%
Financing leases	3.07%
TNMP
Weighted average remaining lease term (years):
Operating leases	2 years 4 months 6 days
Financing leases	3 years 5 months 23 days
Weighted average discount rate:
Operating leases	4.00%
Financing leases	3.09%