Farmer Mac Guaranteed Securities and USDA Securities - Narrative (Details) - AgVantage $ in Millions	Jul. 01, 2023 USD ($)	Sep. 30, 2023 security	Dec. 31, 2022 security
Debt Securities, Available-for-sale [Line Items]
Held-to-maturity, transfer in | $	$ 2,700.0
Held-to-maturity, transfer in, unrealized loss | $	31.9
Held-to-maturity, transfer in, accumulated unrealized loss | $	$ 31.9
Farmer Mac Guaranteed Securities
Debt Securities, Available-for-sale [Line Items]
Available-for-sale, securities in unrealized loss positions		76	95
Held-to-maturity, securities in unrealized loss positions		59	37
Unrealized loss position for more than 12 months, Number of securities in loss position		64	13
Debt securities, held-to-maturity, unrealized loss position for more than 12 months, Number of securities in loss position		26	4