SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES - Schedule of Consolidation of Variable Interest Entities (Details) - USD ($) $ in Thousands	9 Months Ended	12 Months Ended
	Sep. 30, 2026	Dec. 31, 2025	Sep. 30, 2025
Variable Interest Entity [Line Items]
Carrying Value of Assets	$ 40,021,386	$ 35,370,157	$ 33,379,560
Carrying Value of Liabilities	$ 38,178,741	$ 33,651,208
Farmer Mac Guaranteed Securities
Variable Interest Entity [Line Items]
Weighted-average remaining maturity	19 years 10 months 24 days	20 years 8 months 12 days
Unconsolidated VIE | Farmer Mac Guaranteed Securities
Variable Interest Entity [Line Items]
Max Exposure to Loss	$ 439,179	$ 466,441
Carrying Value of Assets	81,267	85,791
Carrying Value of Liabilities	$ 4,681	$ 5,020