Securities - Held to Maturity, Credit Quality (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Dec. 31, 2024
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	$ 336,928	$ 339,436
Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	7,337	7,350
Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	155,910	156,305
Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	46,031	45,964
Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	955	954
AAA
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	41,926	42,323
AAA \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	7,337	7,350
AAA \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	34,589	34,973
AAA \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
AAA \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
AA
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	102,609	101,112
AA \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
AA \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	102,609	101,112
AA \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
AA \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
A
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	6,963	8,478
A \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
A \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	1,960	3,473
A \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	5,003	5,005
A \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
BBB
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	36,754	36,697
BBB \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
BBB \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	650	652
BBB \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	36,104	36,045
BBB \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
BB
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	1,967	1,963
BB \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
BB \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
BB \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	1,967	1,963
BB \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
Non-rated
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	20,014	20,000
Non-rated \| Private label mortgage-backed
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	0	0
Non-rated \| Obligations of states and political subdivisions
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	16,102	16,095
Non-rated \| Corporate
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	2,957	2,951
Non-rated \| Trust preferred
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	955	954
Credit Rated and Non-rated Securities HTM
Debt Securities, Held-to-Maturity, Fair Value to Amortized Cost, after Allowance for Credit Loss [Abstract]
Carrying value	$ 210,233	$ 210,573

INDEPENDENT BANK CORP /MI/ 10-Q