Regulatory Matters (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Banking Regulation, Tier 1 Leverage Capital [Abstract]
Capital conservation buffer	0.0250	0.0250
Components of regulatory capital [Abstract]
Total shareholders' equity	$ 367,714	$ 347,596	$ 355,449	$ 398,484
Add (deduct)
Accumulated other comprehensive loss	(80,811)	(92,763)
Subordinated debt	$ 39,452	39,433
Period of transition method for regulatory purposes	3 years
Consolidated
Banking Regulation, Total Capital [Abstract]
Total risk-based capital	$ 542,176	$ 536,549
Actual, ratio	0.1380	0.1362
Banking regulation, total risk-based capital, capital adequacy, minimum	$ 314,237	$ 315,059
Minimum for adequately capitalized institutions, ratio	0.0800	0.0800
Tier 1 capital to risk-weighted assets [Abstract]
Actual, amount	$ 453,041	$ 447,299
Banking regulation, tier 1 risk-based capital ratio, accrual	0.1153	0.1136
Minimum for adequately capitalized institutions, amount	$ 235,678	$ 236,294
Minimum for adequately capitalized institutions, ratio	0.0600	0.0600
Common equity tier 1 capital to risk-weighted assets [Abstract]
Actual, amount	$ 414,588	$ 408,863
Actual, ratio	0.1055	0.1038
Minimum for adequately capitalized institutions, amount	$ 176,758	$ 177,221
Minimum for adequately capitalized institutions, ratio	0.0450	0.0450
Banking Regulation, Tier 1 Leverage Capital [Abstract]
Tier 1 capital	$ 453,041	$ 447,299
Actual, ratio	0.0892	0.0886
Minimum for adequately capitalized institutions, amount	$ 203,233	$ 201,875
Minimum for adequately capitalized institutions, ratio	0.0400	0.0400
Components of regulatory capital [Abstract]
Total shareholders' equity	$ 367,714	$ 347,596
Add (deduct)
Accumulated other comprehensive loss	75,013	86,966
Goodwill and other intangibles	(30,715)	(30,851)
CECL	2,576	5,152
Common equity tier 1 capital	414,588	408,863
Qualifying trust preferred securities	38,453	38,436
Tier 1 capital	453,041	447,299
Subordinated debt	40,000	40,000
Allowance for credit losses and allowance for unfunded lending commitments limited to 1.25% of total risk-weighted assets	49,135	49,250
Total risk-based capital	542,176	536,549
Independent Bank
Banking Regulation, Total Capital [Abstract]
Total risk-based capital	$ 486,461	$ 480,886
Actual, ratio	0.1240	0.1222
Banking regulation, total risk-based capital, capital adequacy, minimum	$ 313,901	$ 314,733
Minimum for adequately capitalized institutions, ratio	0.0800	0.0800
Minimum for well-capitalized institutions, amount	$ 392,377	$ 393,416
Minimum for well-capitalized institutions, ratio	0.1000	0.1000
Tier 1 capital to risk-weighted assets [Abstract]
Actual, amount	$ 437,377	$ 431,685
Banking regulation, tier 1 risk-based capital ratio, accrual	0.1115	0.1097
Minimum for adequately capitalized institutions, amount	$ 235,426	$ 236,049
Minimum for adequately capitalized institutions, ratio	0.0600	0.0600
Minimum for well-capitalized institutions, amount	$ 313,901	$ 314,733
Minimum for well capitalized institutions, ratio	0.0800	0.0800
Common equity tier 1 capital to risk-weighted assets [Abstract]
Actual, amount	$ 437,377	$ 431,685
Actual, ratio	0.1115	0.1097
Minimum for adequately capitalized institutions, amount	$ 176,569	$ 177,037
Minimum for adequately capitalized institutions, ratio	0.0450	0.0450
Minimum for well-capitalized institutions, amount	$ 255,045	$ 255,720
Minimum for well-capitalized institutions, ratio	0.0650	0.0650
Banking Regulation, Tier 1 Leverage Capital [Abstract]
Tier 1 capital	$ 437,377	$ 431,685
Actual, ratio	0.0861	0.0856
Minimum for adequately capitalized institutions, amount	$ 203,239	$ 201,820
Minimum for adequately capitalized institutions, ratio	0.0400	0.0400
Banking regulation, tier 1 leverage, capital, well capitalized, minimum	$ 254,048	$ 252,275
Minimum for well capitalized institutions, ratio	0.0500	0.0500
Components of regulatory capital [Abstract]
Total shareholders' equity	$ 390,503	$ 370,418
Add (deduct)
Accumulated other comprehensive loss	75,013	86,966
Goodwill and other intangibles	(30,715)	(30,851)
CECL	2,576	5,152
Common equity tier 1 capital	437,377	431,685
Qualifying trust preferred securities	0	0
Tier 1 capital	437,377	431,685
Subordinated debt	0	0
Allowance for credit losses and allowance for unfunded lending commitments limited to 1.25% of total risk-weighted assets	49,084	49,201
Total risk-based capital	$ 486,461	$ 480,886