v3.26.3
Equity Offerings, Offering Expenses, and Distributions - Common Stock Narrative (Details) - USD ($)
 3 Months Ended 12 Months Ended
Feb. 10, 2026
Oct. 30, 2020
Aug. 03, 2020
Sep. 30, 2026
Sep. 30, 2025
Jun. 30, 2026
Jun. 30, 2025
Aug. 19, 2026
Aug. 18, 2026
Jul. 07, 2026
May 06, 2026
May 21, 2020
Aug. 24, 2011
Class of Stock [Line Items]                          
Stock repurchase program, authorized amount                         $ 100,000,000
Stock repurchase program, remaining authorized repurchase amount       $ 65,860,000                  
Market price threshold                       95.00%  
Common stock, shares authorized (in shares)       3,235,276,407   1,233,321,471              
Outstanding shares threshold                   25.00%      
Payments of dividends, common stock       $ 55,256,000 $ 62,393,000                
Issuable Upon Conversion                          
Class of Stock [Line Items]                          
Capital shares reserved for future issuance (in shares)       987,634,200                  
Issuable to Common Stock Holders Pursuant to Dividend Reinvestment and Direct Stock Purchase Plans                          
Class of Stock [Line Items]                          
Capital shares reserved for future issuance (in shares)       86,081,949                  
O 2027 M4 Dividends                          
Class of Stock [Line Items]                          
Dividends payable (usd per share)       $ 0.035                  
Valley Electric Company, Inc.                          
Class of Stock [Line Items]                          
Common stock, shares authorized (in shares)               4,000,000,000 2,000,000,000        
5.50% Preferred Stock                          
Class of Stock [Line Items]                          
Dividend rate 5.50% 5.50%   5.50% 5.50% 5.50% 5.50%            
Dividend rate     5.50% 5.50% 5.50%                
5.50% Preferred Stock | O 2027 M4 Dividends                          
Class of Stock [Line Items]                          
Dividends payable (usd per share)       $ 0.114583                  
6.50% Preferred Stock                          
Class of Stock [Line Items]                          
Dividend rate       6.50% 6.50% 6.50% 6.50%            
Dividend rate     6.50% 6.50% 6.50%                
6.50% Preferred Stock | O 2027 M4 Dividends                          
Class of Stock [Line Items]                          
Dividends payable (usd per share)       $ 0.135417                  
Common Stock                          
Class of Stock [Line Items]                          
Stock repurchased during period (in shares)       0 0                
Shares issued (in shares)       0 0                
Shares issued through reinvestment of dividends (in shares)       3,083,229 2,362,606                
Preferred Stock to Common Stock | InspereX LLC Dealer Manager Agreement                          
Class of Stock [Line Items]                          
Authorized and unissued shares of common stock reclassified into shares of preferred stock (in shares)                     80,000,000