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Consolidated Statements Of Equity And Redeemable Noncontrolling Interests - USD ($) $ in Thousands | Total | Common Stock [Member] | AOCI Attributable to Parent [Member] | Retained Earnings [Member] | Noncontrolling Interests [Member]
--- | --- | --- | --- | --- | ---
Beginning Balance (in shares) at Dec. 31, 2016 |  | 64,187,934 |  |  |
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Shares issued |  | 221,049 |  |  |
Ending Balance (in shares) at Jun. 30, 2017 |  | 64,408,983 |  |  |
Beginning Balance at Dec. 31, 2016 |  | $ 1,075,281 | $ (7,568) | $ 581,014 |
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Equity compensation expense |  | 2,559 |  |  |
Issuance of common stock, net of issuance costs |  | 1,247 |  |  |
Payment of minimum tax withholdings for share-based payment awards |  | (3,420) |  |  |
Other comprehensive income | $ 366 |  | 366 |  |
Reclassification of excess income tax benefits |  |  | 0 | 0 |
Net income attributable to Avista Corporation shareholders | 83,887 |  |  | 83,887 |
Cash dividends paid (common stock) |  |  |  | (46,193) |
Ending Balance at Jun. 30, 2017 | 1,686,894 | $ 1,075,667 | (7,202) | 618,708 |
Beginning Balance Noncontrolling Interest at Dec. 31, 2016 |  |  |  |  | $ (251)
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Net income (loss) attributable to noncontrolling interests |  |  |  |  | (28)
Cash dividends paid to subsidiary noncontrolling interests |  |  |  |  | 0
Ending Balance Noncontrolling Interest at Jun. 30, 2017 |  |  |  |  | (279)
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Total Avista Corporation shareholders’ equity | 1,687,173 |  |  |  |
Total Avista Corporation shareholders’ equity | $ 1,729,828 |  |  |  |
Beginning Balance (in shares) at Dec. 31, 2017 | 65,494,333 | 65,494,333 |  |  |
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Shares issued |  | 193,159 |  |  |
Ending Balance (in shares) at Jun. 30, 2018 | 65,687,492 | 65,687,492 |  |  |
Beginning Balance at Dec. 31, 2017 | $ 1,730,484 | $ 1,133,448 | (8,090) | 604,470 |
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Equity compensation expense |  | 3,558 |  |  |
Issuance of common stock, net of issuance costs |  | 1,227 |  |  |
Payment of minimum tax withholdings for share-based payment awards |  | (3,929) |  |  |
Other comprehensive income | 408 |  | 408 |  |
Reclassification of excess income tax benefits |  |  | (1,742) | 1,742 |
Net income attributable to Avista Corporation shareholders | 80,467 |  |  | 80,467 |
Cash dividends paid (common stock) |  |  |  | (49,101) |
Ending Balance at Jun. 30, 2018 | 1,762,707 | $ 1,134,304 | $ (9,424) | $ 637,578 |
Beginning Balance Noncontrolling Interest at Dec. 31, 2017 | 656 |  |  |  | 656
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Net income (loss) attributable to noncontrolling interests |  |  |  |  | 133
Cash dividends paid to subsidiary noncontrolling interests |  |  |  |  | (540)
Ending Balance Noncontrolling Interest at Jun. 30, 2018 | 249 |  |  |  | $ 249
Common Stock, Number of Shares, Par Value and Other Disclosures [Abstract] |  |  |  |  |
Total Avista Corporation shareholders’ equity | $ 1,762,458 |  |  |  |

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- Definition Reclassification from AOCI to Retained Earnings -ASU 2018-02 was issued February 2018, which allows stranded tax effects associated with the enactment of the Tax Cuts and Jobs Act to be reclassified from AOCI to Retained Earnings. + References No definition available. + Details
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