Fair Value of Derivative and Other Financial Instruments, Margin, Notional Amounts, Credit Rating (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010
Derivative [Line Items]
Derivative, Collateral, Right to Reclaim Cash	$ 0	$ 3,400,000
Margin Deposit Assets	1,800,000	32,000,000
Contractual Liability		8,113,000
Existing Cash Collateral		0
Net Exposure		2,642,000
PNMR and PNM [Member]
Derivative [Line Items]
Contractual Liability	4,036,000
Existing Cash Collateral	0
Net Exposure	4,036,000
Public Service Company of New Mexico [Member]
Derivative [Line Items]
Derivative, Collateral, Right to Reclaim Cash	0	3,000,000
Margin Deposit Assets	1,800,000	2,100,000
Contractual Liability		291,000
Existing Cash Collateral		0
Net Exposure		$ 119,000
Commodity Contract [Member] | Economic hedges [Member] | Derivative Long Position [Member]
Derivative [Line Items]
Volume positions (Decatherms / MWh)		(1,693,431,000)
Commodity Contract [Member] | Economic hedges [Member] | Derivative Long Position [Member] | PNMR and PNM [Member]
Derivative [Line Items]
Volume positions (Decatherms / MWh)	(1,499,000,000)
Commodity Contract [Member] | Economic hedges [Member] | Derivative Long Position [Member] | Public Service Company of New Mexico [Member]
Derivative [Line Items]
Volume positions (Decatherms / MWh)		(1,882,500,000)
Commodity Contract [Member] | Economic hedges [Member] | Derivative Short Position [Member] | PNMR and PNM [Member]
Derivative [Line Items]
Volume positions (Decatherms / MWh)	(366,448,000)
Commodity Contract [Member] | Economic hedges [Member] | Derivative Short Position [Member] | Public Service Company of New Mexico [Member]
Derivative [Line Items]
Volume positions (Decatherms / MWh)		(990,120,000)