Regulatory Matters (Details) $ in Thousands		3 Months Ended
		Mar. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Mar. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Regulatory Matters [Abstract]
Undivided profits		$ 81,600
Tier 1 capital to average assets [Abstract]
Capital conservation buffer		0.0250	0.0250
Components of regulatory capital [Abstract]
Total shareholders' equity		$ 387,329	$ 389,522	$ 335,618	$ 350,169
Add (deduct) [Abstract]
Accumulated other comprehensive income for regulatory purposes		4,338	10,024
Subordinated debt		$ 39,300	39,281
Period of transition method for regulatory purposes		3 years
Consolidated [Member]
Total capital to risk-weighted assets [Abstract]
Total risk-based capital	[1]	$ 467,880	$ 455,072
Actual, Ratio	[1]	0.1582	0.1595
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 236,589	$ 228,214
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0800	0.0800
Tier 1 capital to risk-weighted assets [Abstract]
Actual, Amount	[1]	$ 390,875	$ 379,395
Actual, Ratio	[1]	0.1322	0.1330
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 177,442	$ 171,161
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0600	0.0600
Common equity tier 1 capital to risk-weighted assets [Abstract]
Actual, Amount	[1]	$ 352,558	$ 341,095
Actual, Ratio	[1]	0.1192	0.1196
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 133,081	$ 128,370
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0450	0.0450
Tier 1 capital to average assets [Abstract]
Tier 1 capital	[1]	$ 390,875	$ 379,395
Actual, Ratio	[1]	0.0928	0.0915
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 168,473	$ 165,825
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0400	0.0400
Components of regulatory capital [Abstract]
Total shareholders' equity		$ 387,329	$ 389,522
Add (deduct) [Abstract]
Accumulated other comprehensive income for regulatory purposes		(10,135)	(15,821)
Goodwill and other intangibles		(32,363)	(32,606)
CECL	[2]	7,727	0
Common equity tier 1 capital	[1]	352,558	341,095
Qualifying trust preferred securities		38,317	38,300
Tier 1 capital	[1]	390,875	379,395
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	[3]	37,005	35,677
Total risk-based capital	[1]	467,880	455,072
Independent Bank [Member]
Total capital to risk-weighted assets [Abstract]
Total risk-based capital	[1]	$ 414,246	$ 401,005
Actual, Ratio	[1]	0.1399	0.1406
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 236,819	$ 228,111
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0800	0.0800
Minimum for Well-Capitalized Institutions, Amount	[1]	$ 296,024	$ 285,139
Minimum for Well-Capitalized Institutions, Ratio	[1]	0.1000	0.1000
Tier 1 capital to risk-weighted assets [Abstract]
Actual, Amount	[1]	$ 377,199	$ 365,343
Actual, Ratio	[1]	0.1274	0.1281
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 177,614	$ 171,083
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0600	0.0600
Minimum for Well-Capitalized Institutions, Amount	[1]	$ 236,819	$ 228,111
Minimum for Well-Capitalized Institutions, Ratio	[1]	0.0800	0.0800
Common equity tier 1 capital to risk-weighted assets [Abstract]
Actual, Amount	[1]	$ 377,199	$ 365,343
Actual, Ratio	[1]	0.1274	0.1281
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 133,211	$ 128,312
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0450	0.0450
Minimum for Well-Capitalized Institutions, Amount	[1]	$ 192,415	$ 185,340
Minimum for Well-Capitalized Institutions, Ratio	[1]	0.0650	0.0650
Tier 1 capital to average assets [Abstract]
Tier 1 capital	[1]	$ 377,199	$ 365,343
Actual, Ratio	[1]	0.0895	0.0881
Minimum for Adequately Capitalized Institutions, Amount	[1]	$ 168,622	$ 165,828
Minimum for Adequately Capitalized Institutions, Ratio	[1]	0.0400	0.0400
Minimum for Well-Capitalized Institutions, Amount	[1]	$ 210,778	$ 207,285
Minimum for Well-Capitalized Institutions, Ratio	[1]	0.0500	0.0500
Components of regulatory capital [Abstract]
Total shareholders' equity		$ 411,970	$ 413,770
Add (deduct) [Abstract]
Accumulated other comprehensive income for regulatory purposes		(10,135)	(15,821)
Goodwill and other intangibles		(32,363)	(32,606)
CECL	[2]	7,727	0
Common equity tier 1 capital	[1]	377,199	365,343
Qualifying trust preferred securities		0	0
Tier 1 capital	[1]	377,199	365,343
Subordinated debt		0	0
Allowance for credit losses and allowance for unfunded lending commitments limited to 1.25% of total risk-weighted assets	[3]	37,047	35,662
Total risk-based capital	[1]	$ 414,246	$ 401,005

[1] These ratios do not reflect a capital conservation buffer of 2.50% at March 31, 2021 and December 31, 2020.

[2] We elected the three year CECL transition method for regulatory purposes.

[3] Beginning January 1, 2021, calculation of allowances are based on CECL methodology. Prior to January 1, 2021, calculation was based on the probable incurred loss methodology.