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Pension and Other Postretirement Benefits - Other Postretirement Benefits (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2016 | Dec. 31, 2015 | Dec. 31, 2014
Other Retirement Plans, 401 (k) plan [Member] |  |  |
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract] |  |  |
401(k) plan | $ 17,762 | $ 16,725 | $ 16,703
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 | 13,397 | 12,679 | 12,745
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 | 4,365 | 4,046 | 3,958
Other Retirement Plans, Key Employees, Non-qualified Plan [Member] |  |  |
Defined Contribution Pension and Other Postretirement Plans Disclosure [Abstract] |  |  |
Non-qualified plan | 2,017 | 1,436 | 2,257
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 | 1,535 | 1,090 | 1,722
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 | $ 482 | $ 346 | $ 535

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- Definition The compensation expense recognized during the period pertaining to the deferred compensation arrangement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 710 -SubTopic 10 -Section 30 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6409875&loc=d3e20015-108363 + Details
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- Definition The amount of the cost recognized during the period for defined contribution plans. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 + Details
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