Financing - Long-term Debt Maturities (Details) - USD ($) $ in Thousands	Dec. 31, 2017	Dec. 31, 2016
Long-term Debt, by Maturity [Abstract]
2018	$ 257,293
2019	384,659
2020	126,207
2021	310,650
2022	57,000
Thereafter	1,295,698
Total	2,431,507	$ 2,388,577
PNMR
Long-term Debt, by Maturity [Abstract]
2018	257,268
2019	12,357
2020	25,862
2021	4,650
2022	0
Thereafter	0
Total	300,137	342,207
Public Service Company of New Mexico
Long-term Debt, by Maturity [Abstract]
2018	25
2019	200,000
2020	100,345
2021	306,000
2022	57,000
Thereafter	1,002,500
Total	1,665,870	1,640,870
Texas-New Mexico Power Company
Long-term Debt, by Maturity [Abstract]
2018	0
2019	172,302
2020	0
2021	0
2022	0
Thereafter	293,198
Total	$ 465,500	$ 405,500