Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	$ 1,466	$ 1,423	$ 1,751
Charged to costs and expenses	3,358	3,267	2,849
Charged to other accounts	0	0	0
Write-offs	3,427	3,224	3,177
Balance at end of year	1,397	1,466	1,423
Public Service Company of New Mexico [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	1,466	1,423	1,751
Charged to costs and expenses	3,344	3,275	2,864
Charged to other accounts	0	0	0
Write-offs	3,413	3,232	3,192
Balance at end of year	1,397	1,466	1,423
Texas-New Mexico Power Company [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at beginning of year	0	0	0
Charged to costs and expenses	14	(8)	(15)
Charged to other accounts	0	0	0
Write-offs	14	(8)	(15)
Balance at end of year	$ 0	$ 0	$ 0