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Regulatory Matters - Schedule of Regulatory Liabilities (Details) - USD ($) $ in Thousands | Sep. 30, 2017 | Dec. 31, 2016
--- | --- | ---
Detail of regulatory liabilities |  |
Regulatory liabilities, current | $ 120,671 | $ 99,899
Regulatory liabilities, non-current | 891,715 | 948,916
Asset retirement obligations |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 0 | 0
Regulatory liabilities, non-current | 313,189 | 279,976
Removal costs |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 37,756 | 29,899
Regulatory liabilities, non-current | 184,512 | 223,145
Other postretirement benefits |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 32,725 | 32,662
Regulatory liabilities, non-current | 99,626 | 123,913
Income taxes — deferred investment tax credit |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 4,315 | 4,368
Regulatory liabilities, non-current | 106,557 | 108,827
Income taxes — change in rates |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 2,565 | 1,771
Regulatory liabilities, non-current | 67,136 | 70,898
Spent nuclear fuel |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 6,562 | 0
Regulatory liabilities, non-current | 64,504 | 71,726
Renewable energy standard (c) |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 17,915 | 26,809
Regulatory liabilities, non-current | 0 | 0
Demand side management (c) |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 12,175 | 0
Regulatory liabilities, non-current | 4,921 | 20,472
Sundance maintenance |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 0 | 0
Regulatory liabilities, non-current | 16,494 | 15,287
Deferred gains on utility property |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 4,525 | 2,063
Regulatory liabilities, non-current | 11,875 | 8,895
Four Corners coal reclamation |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 1,857 | 0
Regulatory liabilities, non-current | 19,494 | 18,248
Other |  |
Detail of regulatory liabilities |  |
Regulatory liabilities, current | 276 | 2,327
Regulatory liabilities, non-current | $ 3,407 | $ 7,529

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- Definition The amount for the individual regulatory current liability including deferred fuel and purchased power as itemized in a table of regulatory current liabilities as of the end of the period. + References No definition available. + Details
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- Definition The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
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