Income Taxes - Schedule of Components of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Taxes [Line Items]
Current federal income tax	$ 0	$ 0	$ (2,015)
Current state income tax	(527)	(1,376)	(728)
Deferred federal income tax	60,892	5,488	59,814
Deferred state income tax	3,886	12,305	14,831
Amortization of accumulated investment tax credits	(973)	(1,342)	(2,164)
Total income taxes (benefit)	63,278	15,075	69,738
Public Service Company of New Mexico [Member]
Income Taxes [Line Items]
Current federal income tax	(10,290)	(7,934)	(2,175)
Current state income tax	(1,907)	(1,988)	(979)
Deferred federal income tax	49,123	(6,827)	45,890
Deferred state income tax	4,969	5,333	12,061
Amortization of accumulated investment tax credits	(973)	(1,342)	(2,164)
Total income taxes (benefit)	40,922	(12,758)	52,633
Texas-New Mexico Power Company [Member]
Income Taxes [Line Items]
Current federal income tax	9,445	1,603	35
Current state income tax	1,729	1,639	1,939
Deferred federal income tax	12,690	20,904	20,577
Deferred state income tax	(28)	(21)	(28)
Total income taxes (benefit)	$ 23,836	$ 24,125	$ 22,523