Lease Commitments - Finance Lease Balance Sheet Information (Details) - USD ($) $ in Thousands	Sep. 30, 2020	Dec. 31, 2019
Financing leases:
Non-utility property	$ 21,841	$ 10,028
Accumulated depreciation	(3,159)	(973)
Non-utility property, net	18,682	9,055
Other current liabilities	3,829	1,637
Other deferred credits	14,603	7,102
PNM
Financing leases:
Non-utility property	10,491	4,857
Accumulated depreciation	(1,503)	(482)
Non-utility property, net	8,988	4,375
Other current liabilities	1,804	722
Other deferred credits	6,924	3,333
TNMP
Financing leases:
Non-utility property	11,047	4,910
Accumulated depreciation	(1,576)	(466)
Non-utility property, net	9,471	4,444
Other current liabilities	1,946	850
Other deferred credits	$ 7,532	$ 3,597