v3.25.2
Computation of Earnings Per Common Share (Schedule of Earnings Per Share) (Details) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 30, 2025
Jun. 30, 2024
Jun. 30, 2025
Jun. 30, 2024
Earnings Per Share [Abstract]        
Average number of common shares outstanding for basic calculation 7,383,338 7,477,310 7,400,370 7,485,743
Average number of common shares outstanding used to calculate diluted earnings per common share 7,398,109 7,494,828 7,413,974 7,501,437
Net income $ 5,031 $ 3,481 $ 8,980 $ 6,612
Basic (in dollars per share) $ 0.68 $ 0.47 $ 1.21 $ 0.88
Diluted (in dollars per share) $ 0.68 $ 0.46 $ 1.21 $ 0.88
Isabella Bank Corporation Restricted Stock Plan        
Earnings Per Share [Abstract]        
Average potential effect of common shares in the Directors Plan 14,771 17,518 13,604 15,694
Earnings Per Share, Diluted, by Common Class, Including Two Class Method [Line Items]        
Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements 14,771 17,518 13,604 15,694