Common Stock Common Stock (Notes)

3 Months Ended

Mar. 31, 2018

Stockholders' Equity Note [Abstract]

Stockholders' Equity Note Disclosure [Text Block]

COMMON STOCK

The Company has entered into four separate sales agency agreements under which Avista Corp.'s sales agents may offer and sell up to 3.8 million new shares of Avista Corp.'s common stock, no par value, from time to time. The sales agency agreements expire on February 29, 2020 and as of March 31, 2018, the Company has 1.1 million shares remaining to be issued under these agreements. No shares were issued under these agreements in the three months endedMarch 31, 2018.