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Schedule II - Valuation and Qualifying Accounts (Details) - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2016
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at beginning of year | $ 1,081 | $ 1,209 | $ 1,397
Charged to costs and expenses | 3,360 | 2,619 | 2,885
Charged to other accounts | 0 | 0 | 0
Write-offs | 3,035 | 2,747 | 3,073
Balance at end of year | 1,406 | 1,081 | 1,209
Public Service Company of New Mexico |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at beginning of year | 1,081 | 1,209 | 1,397
Charged to costs and expenses | 3,338 | 2,615 | 2,871
Charged to other accounts | 0 | 0 | 0
Write-offs | 3,013 | 2,743 | 3,059
Balance at end of year | 1,406 | 1,081 | 1,209
Texas-New Mexico Power Company |  |  |
SEC Schedule, 12-09, Movement in Valuation Allowances and Reserves [Roll Forward] |  |  |
Balance at beginning of year | 0 | 0 | 0
Charged to costs and expenses | 22 | 4 | 14
Charged to other accounts | 0 | 0 | 0
Write-offs | 22 | 4 | 14
Balance at end of year | $ 0 | $ 0 | $ 0

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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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