Fair Value of Derivative and Other Financial Instruments, Derivative Balance Sheet Information (Details) (USD $)	Dec. 31, 2012	Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, Current assets	$ 3,785,000	$ 3,713,000
Commodity derivative instruments, Deferred charges	352,000	0
Commodity derivative instruments, Current liabilities	(1,000,000)	(1,632,000)
Commodity derivative instruments, Long-term liabilities	(1,933,000)	(2,437,000)
PNMR and PNM [Member]
Derivatives, Fair Value [Line Items]
Margin Deposit Assets	1,900,000	1,800,000
Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, Current assets	3,785,000	3,713,000
Commodity derivative instruments, Deferred charges	352,000	0
Commodity derivative instruments, Current liabilities	(1,000,000)	(1,632,000)
Commodity derivative instruments, Long-term liabilities	(1,933,000)	(2,437,000)
Commodity Contract [Member] | Economic hedges [Member] | PNMR and PNM [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, Current assets	3,785,000	3,713,000
Commodity derivative instruments, Deferred charges	352,000	0
Commodity derivative instruments, Assets	4,137,000	3,713,000
Commodity derivative instruments, Current liabilities	(1,000,000)	(1,632,000)
Commodity derivative instruments, Long-term liabilities	(1,933,000)	(2,437,000)
Commodity derivative instruments, Liabilities	(2,933,000)	(4,069,000)
Commodity derivative instruments, Net	1,204,000	(356,000)
Commodity Contract [Member] | Fuel and purchased power adjustment clause [Member] | Economic hedges [Member] | Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, Current assets	$ 100,000	$ 500,000