Schedule II - Valuation and Qualifying Accounts (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011		Dec. 31, 2010
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	$ 1,778	$ 11,178	[1]	$ 12,783
Charged to costs and expenses	3,367	24,116		27,566
Charged to other accounts	0	0		0
Write-offs and other	3,394	33,516	[1]	29,171
Balance at end of year	1,751	1,778		11,178	[1]
Public Service Company of New Mexico [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	1,778	1,483		1,483
Charged to costs and expenses	3,384	3,736		2,600
Charged to other accounts	0	0		0
Write-offs and other	3,411	3,441		2,600
Balance at end of year	1,751	1,778		1,483
Texas-New Mexico Power Company [Member]
Valuation and Qualifying Accounts Disclosure [Line Items]
Balance at beginning of year	0	0		0
Charged to costs and expenses	(17)	33		22
Charged to other accounts	0	0		0
Write-offs and other	(17)	33		22
Balance at end of year	$ 0	$ 0		$ 0

[1] Includes reduction of $11,818 due to the sale of First Choice on November 1, 2011.