Financing, Financing Activities (Details) (USD $)											0 Months Ended			0 Months Ended
	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2013 Public Service Company of New Mexico [Member]	Dec. 31, 2012 Public Service Company of New Mexico [Member]	Mar. 31, 2013 Texas-New Mexico Power Company [Member]	Dec. 31, 2012 Texas-New Mexico Power Company [Member]	Mar. 31, 2013 PNMR Term Loan Agreement [Member]	Dec. 31, 2012 PNMR Term Loan Agreement [Member]	Mar. 06, 2013 First Mortgage Bonds [Member] First Mortgage Bonds Due 2014, Series 2009A, at 9 point 50 percent [Member] Texas-New Mexico Power Company [Member]	Mar. 06, 2013 First Mortgage Bonds [Member] First Mortgage Bonds, due 2043, Series 2013A [Member] Texas-New Mexico Power Company [Member]	Apr. 22, 2013 Subsequent Event [Member] First Mortgage Bonds [Member] Texas-New Mexico Power Company [Member]	Apr. 03, 2013 Subsequent Event [Member] First Mortgage Bonds [Member] First Mortgage Bonds Due 2014, Series 2009A, at 9 point 50 percent [Member] Texas-New Mexico Power Company [Member]	Apr. 03, 2013 Subsequent Event [Member] First Mortgage Bonds [Member] First Mortgage Bonds, due 2043, Series 2013A [Member] Texas-New Mexico Power Company [Member]	Apr. 22, 2013 Notes Payable to Banks [Member] Subsequent Event [Member] PNM Term Loan Agreement [Member]
Debt Instrument [Line Items]
Debt Instrument, Face Amount									$ 265,500,000				$ 93,200,000
Debt Instrument, Interest Rate, Stated Percentage									9.50%	6.95%		9.50%	6.95%
Debt Instrument, Cash Paid for Debt Exchanged											13,000,000
Debt Instrument, Cash for Bond Exchange Conversion										0.14
Debt Instrument, Unamortized Premium													23,200,000
Short-term debt	243,300,000	158,700,000	88,900,000	21,100,000	25,000,000	0	100,000,000	100,000,000						75,000,000
Repayments of Lines of Credit														$ 75,000,000