Parent Company Only Financial Information (Interim Condensed Statements of Cash Flows) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021
Operating activities
NET INCOME	$ 10,029	$ 10,019
Adjustments to reconcile net income to cash provided by operations
Depreciation	1,077	1,196
Changes in operating assets and liabilities which used cash
Accrued interest receivable and other assets	1,848	2,923
Accrued interest and other liabilities	(35)	(258)
Net cash provided by (used in) operating activities	14,780	15,861
Investing activities
Net cash provided by (used in) investing activities	(70,681)	(81,218)
Financing activities
Proceeds from Issuance of Subordinated Long-term Debt	0	29,114
Cash dividends paid on common stock	(4,007)	(4,275)
Proceeds from the issuance of common stock	907	806
Common stock repurchased	(397)	(1,860)
Common stock purchased for deferred compensation obligations	(527)	(595)
Net cash provided by (used in) financing activities	32,588	66,906
Increase (decrease) in cash and cash equivalents	(23,313)	1,549
Cash and cash equivalents at beginning of period	105,330	246,640
Cash and cash equivalents at end of period	82,017	248,189
Amortization of Debt Issuance Costs	45	7
Isabella Bank Corporation Restricted Stock Plan
Adjustments to reconcile net income to cash provided by operations
Share-based payment awards	77	25
Isabella Bank Corporation and Related Companies Deferred Compensation Plan for Directors
Adjustments to reconcile net income to cash provided by operations
Share-based payment awards	249	256
Parent Company [Member]
Operating activities
NET INCOME	10,029	10,019
Adjustments to reconcile net income to cash provided by operations
Undistributed earnings of subsidiaries	(9,513)	(8,892)
Depreciation	26	25
Changes in operating assets and liabilities which used cash
Accrued interest receivable and other assets	1,275	552
Accrued interest and other liabilities	(51)	175
Net cash provided by (used in) operating activities	2,137	2,167
Financing activities
Proceeds from Issuance of Subordinated Long-term Debt	0	(29,114)
Cash dividends paid on common stock	(4,007)	(4,275)
Proceeds from the issuance of common stock	907	806
Common stock repurchased	(397)	(1,860)
Common stock purchased for deferred compensation obligations	(527)	(595)
Net cash provided by (used in) financing activities	(4,024)	23,190
Increase (decrease) in cash and cash equivalents	(1,887)	25,357
Cash and cash equivalents at beginning of period	11,535	2,670
Cash and cash equivalents at end of period	9,648	28,027
Amortization of Debt Issuance Costs	45	7
Parent Company [Member] | Isabella Bank Corporation Restricted Stock Plan
Adjustments to reconcile net income to cash provided by operations
Share-based payment awards	77	25
Parent Company [Member] | Isabella Bank Corporation and Related Companies Deferred Compensation Plan for Directors
Adjustments to reconcile net income to cash provided by operations
Share-based payment awards	$ 249	$ 256