Lease Commitments - Operating Lease Balance Sheet Information (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021
Operating leases:
Operating lease assets, net of amortization	$ 74,126	$ 79,511
Current portion of operating lease liabilities	27,722	27,218
Long-term portion of operating lease liabilities	47,369	55,993
PNM
Operating leases:
Operating lease assets, net of amortization	69,022	73,903
Current portion of operating lease liabilities	25,826	25,278
Long-term portion of operating lease liabilities	44,377	52,552
TNMP
Operating leases:
Operating lease assets, net of amortization	4,782	5,264
Current portion of operating lease liabilities	1,853	1,882
Long-term portion of operating lease liabilities	$ 2,713	$ 3,155