XML 125 R1.htm IDEA: XBRL DOCUMENT v3.19.3.a.u2
Document and Entity Information Document - USD ($)
 12 Months Ended
Dec. 31, 2019
Jan. 31, 2020
Jun. 30, 2019
Cover page.      
Entity Filer Category Large Accelerated Filer    
Title of 12(b) Security Common Stock    
Entity Incorporation, State or Country Code WA    
Entity Registrant Name AVISTA CORPORATION    
Document Transition Report false    
Document Annual Report true    
Document Type 10-K    
Document Period End Date Dec. 31, 2019    
Entity File Number 001-03701    
Entity Tax Identification Number 91-0462470    
Entity Address, Address Line One 1411 East Mission Avenue    
Entity Address, City or Town Spokane    
Entity Address, State or Province WA    
Entity Address, Postal Zip Code 99202-2600    
City Area Code 509    
Local Phone Number 489-0500    
Trading Symbol AVA    
Security Exchange Name NYSE    
Entity Well-known Seasoned Issuer Yes    
Entity Voluntary Filers No    
Entity Current Reporting Status Yes    
Entity Interactive Data Current Yes    
Entity Small Business false    
Entity Emerging Growth Company false    
Entity Shell Company false    
Entity Public Float     $ 2,948,564,738
Entity Common Stock, Shares Outstanding   67,208,604  
Amendment Flag false    
Document Fiscal Year Focus 2019    
Document Fiscal Period Focus FY    
Entity Central Index Key 0000104918    
Current Fiscal Year End Date --12-31    
Documents Incorporated by Reference [Text Block]
Documents Incorporated By Reference
Document
 
Part of Form 10-K into Which
Document is Incorporated
Proxy Statement to be filed in connection with the annual meeting of shareholders to be held on May 11, 2020.
Prior to such filing, the Proxy Statement filed in connection with the annual meeting of shareholders held on May 9, 2019.
 
Part III, Items 10, 11,
12, 13 and 14