Investment Securities - Schedule of Amortized Cost and Estimated Fair Value of Securities Available-for-Sale and Held-to-Maturity (Details) - USD ($) $ in Thousands	Sep. 30, 2025	Dec. 31, 2024
Securities Available-for-Sale:
Amortized Cost	$ 336,310	$ 409,380
Gross Unrealized Gains	465	225
Gross Unrealized Losses	(31,516)	(43,556)
Fair Value	305,259	366,049
Securities Held-to-Maturity:
Amortized Cost	389,135	430,077
Gross Unrealized Gains	44	0
Gross Unrealized Losses	(35,561)	(47,057)
Fair Value	353,618	383,020
U.S. treasury securities
Securities Available-for-Sale:
Amortized Cost	766	3,173
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(3)	0
Fair Value	763	3,173
Securities Held-to-Maturity:
Amortized Cost	65,126	91,004
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(1,244)	(2,828)
Fair Value	63,882	88,176
U.S. agency securities
Securities Available-for-Sale:
Amortized Cost	2,265	3,001
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(120)	(246)
Fair Value	2,145	2,755
Securities Held-to-Maturity:
Amortized Cost	9,048	16,151
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(736)	(1,263)
Fair Value	8,312	14,888
Asset backed securities
Securities Available-for-Sale:
Amortized Cost	15,033	17,925
Gross Unrealized Gains	18	17
Gross Unrealized Losses	(206)	(118)
Fair Value	14,845	17,824
State, county & municipal securities
Securities Available-for-Sale:
Amortized Cost	109,984	110,952
Gross Unrealized Gains	9	0
Gross Unrealized Losses	(12,348)	(15,315)
Fair Value	97,645	95,637
Securities Held-to-Maturity:
Amortized Cost	137,491	137,190
Gross Unrealized Gains	44	0
Gross Unrealized Losses	(13,257)	(15,915)
Fair Value	124,278	121,275
Corporate debt securities
Securities Available-for-Sale:
Amortized Cost	49,816	53,324
Gross Unrealized Gains	19	1
Gross Unrealized Losses	(3,986)	(5,543)
Fair Value	45,849	47,782
Mortgage-backed securities
Securities Available-for-Sale:
Amortized Cost	158,446	221,005
Gross Unrealized Gains	419	207
Gross Unrealized Losses	(14,853)	(22,334)
Fair Value	144,012	198,878
Securities Held-to-Maturity:
Amortized Cost	177,470	185,732
Gross Unrealized Gains	0	0
Gross Unrealized Losses	(20,324)	(27,051)
Fair Value	$ 157,146	$ 158,681

COLONY BANKCORP INC 10-Q