ORGANIZATION AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Recently Adopted Accounting Pronouncements (Details) - USD ($) $ in Thousands		Dec. 31, 2023		Jan. 01, 2023	Dec. 31, 2022		Dec. 31, 2021
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity		$ 242,738			$ 240,864		$ 219,041
Allowance for credit losses		23,931	[1]	$ 20,653	17,183	[1]	13,732
Allowance for credit losses on off-balance sheet exposures				3,900
Allowance for credit losses: held-to-maturity securities				71
Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity		$ 51,042			51,887		$ 30,189
Cumulative change in accounting principle
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity	[2]				(5,319)
Cumulative change in accounting principle | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity					3,470
Cumulative change in accounting principle | Retained Earnings
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity	[2]				$ (5,319)
Cumulative change in accounting principle | Retained Earnings | Accounting Standards Update 2016-13
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total FMC stockholders’ equity				5,300
Allowance for credit losses				3,500
Allowance for credit losses on off-balance sheet exposures				3,500
Allowance for credit losses: held-to-maturity securities				$ 100

[1] Allowance for credit loss amounts for periods prior to the ASC 326 adoption date of January 1, 2023 are reported in accordance with previously applicable GAAP

[2] Refer to Note 1 – Organization and Summary of Significant Accounting Policies for further information