Fair Value of Derivative and Other Financial Instruments, Derivative Balance Sheet Information (Details) (USD $)	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012
Derivatives, Fair Value [Line Items]
Assets, Current	$ 393,157,000		$ 442,191,000
Commodity derivative instruments, Current assets	2,870,000		3,785,000
Commodity derivative instruments, Deferred charges	202,000		352,000
Commodity derivative instruments, Current liabilities		(1,621,000)	(1,000,000)
Commodity derivative instruments, Long-term liabilities		(1,540,000)	(1,933,000)
PNMR and PNM [Member]
Derivatives, Fair Value [Line Items]
Margin Deposit Assets	2,000,000		1,900,000
Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Assets, Current	384,105,000		387,689,000
Commodity derivative instruments, Current assets	2,870,000		3,785,000
Commodity derivative instruments, Deferred charges	202,000		352,000
Commodity derivative instruments, Current liabilities		(1,621,000)	(1,000,000)
Commodity derivative instruments, Long-term liabilities		(1,540,000)	(1,933,000)
Commodity Contract [Member] | Fair Value Hedging [Member] | PNMR and PNM [Member]
Derivatives, Fair Value [Line Items]
Commodity derivative instruments, Current assets	2,870,000		3,785,000
Commodity derivative instruments, Deferred charges	202,000		352,000
Commodity derivative instruments, Assets	3,072,000		4,137,000
Commodity derivative instruments, Current liabilities	(1,621,000)		(1,000,000)
Commodity derivative instruments, Long-term liabilities	(1,540,000)		(1,933,000)
Commodity derivative instruments, Liabilities	(3,161,000)		(2,933,000)
Commodity derivative instruments, Net	(89,000)		1,204,000
Commodity Contract [Member] | Fuel and Purchased Power Adjustment Clause [Member] | Fair Value Hedging [Member] | Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Assets, Current	$ 500,000		$ 100,000
Firm Contract [Member] | Public Service Company of New Mexico [Member]
Derivatives, Fair Value [Line Items]
Percentage of Electric Power Plant Output Sold through 2013	100.00%
Percentage of Electric Power Plant Output Sold for 2014 and 2015	100.00%