INVESTMENT SECURITIES - Amortized cost and fair value (Details) - USD ($)	3 Months Ended
Mar. 31, 2026	Mar. 31, 2025	Dec. 31, 2025
INVESTMENT SECURITIES
Amortized Cost	$ 5,613,360		$ 5,668,833
Gross Unrealized Gains	6,835		9,234
Gross Unrealized Losses	150,937		139,375
Available-for-sale securities	5,469,258		5,538,692
Sale of available-for-sale securities	0	$ 0
Municipal securities
INVESTMENT SECURITIES
Amortized Cost	2,836,073		2,837,990
Gross Unrealized Gains	1,913		2,253
Gross Unrealized Losses	3,535		4,207
Available-for-sale securities	2,834,451		2,836,036
Collateralized mortgage obligation bonds
INVESTMENT SECURITIES
Amortized Cost	47,340		50,980
Gross Unrealized Losses	1,327		1,263
Available-for-sale securities	46,013		49,717
U.S. government agencies
INVESTMENT SECURITIES
Amortized Cost	1,497,851		1,497,747
Gross Unrealized Losses	68,954		59,911
Available-for-sale securities	1,428,897		1,437,836
Mortgage-backed securities
INVESTMENT SECURITIES
Amortized Cost	1,232,096		1,282,116
Gross Unrealized Gains	4,922		6,981
Gross Unrealized Losses	77,121		73,994
Available-for-sale securities	$ 1,159,897		$ 1,215,103

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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