Lease Commitments - Components of Lease Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 29,270	$ 30,418
Amounts capitalized	(2,951)	(3,395)
Total operating lease expense	26,319	27,023
Financing lease cost:
Amortization of right-of-use assets	5,277	3,412
Interest on lease liabilities	574	511
Amounts capitalized	(4,404)	(2,810)
Total financing lease expense	1,447	1,113
Variable lease expense	380	221
Short-term lease expense (1)	3,035	295
Total lease expense for the period	31,181	28,652
Cooling Towers
Financing lease cost:
Short-term lease expense (1)	2,500
Insurance settlements receivable	1,800
Public Service Company of New Mexico
Lessee, Lease, Description [Line Items]
Operating lease cost	26,690	27,302
Amounts capitalized	(836)	(1,020)
Total operating lease expense	25,854	26,282
Financing lease cost:
Amortization of right-of-use assets	2,507	1,563
Interest on lease liabilities	263	221
Amounts capitalized	(1,726)	(1,056)
Total financing lease expense	1,044	728
Variable lease expense	380	221
Short-term lease expense (1)	2,972	288
Total lease expense for the period	30,250	27,519
Texas-New Mexico Power Company
Lessee, Lease, Description [Line Items]
Operating lease cost	2,445	2,870
Amounts capitalized	(2,115)	(2,375)
Total operating lease expense	330	495
Financing lease cost:
Amortization of right-of-use assets	2,682	1,775
Interest on lease liabilities	307	285
Amounts capitalized	(2,678)	(1,754)
Total financing lease expense	311	306
Variable lease expense	0	0
Short-term lease expense (1)	6	5
Total lease expense for the period	$ 647	$ 806