Pension and Other Postretirement Benefits Other Postretirement Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Other Retirement Plans, 401 (k) plan [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
401(k) plan	$ 16,725	$ 16,703	$ 16,785
Other Retirement Plans, 401 (k) plan [Member] | Public Service Company of New Mexico [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
401(k) plan	12,679	12,745	12,952
Other Retirement Plans, 401 (k) plan [Member] | Texas-New Mexico Power Company [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
401(k) plan	4,046	3,958	3,953
Other Retirement Plans, Key Employees, Non-qualified Plan [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Non-qualified plan	1,436	2,257	2,204
Other Retirement Plans, Key Employees, Non-qualified Plan [Member] | Public Service Company of New Mexico [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Non-qualified plan	1,090	1,722	1,691
Other Retirement Plans, Key Employees, Non-qualified Plan [Member] | Texas-New Mexico Power Company [Member]
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract]
Non-qualified plan	$ 346	$ 535	$ 513