Summary of Significant Accounting Policies - Consolidation of Variable Interest Entities (Details) - USD ($) $ in Thousands	Sep. 30, 2023	Dec. 31, 2022
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	$ 9,130,933	$ 9,008,979
Debt securities of consolidated trusts held by third parties	25,602,487	25,000,199
Farmer Mac Guaranteed Securities:
Variable Interest Entity [Line Items]
Carrying value	5,058,697	7,607,226
Investment securities:
Variable Interest Entity [Line Items]
Carrying value	4,873,414	4,579,564
Agricultural Finance
Variable Interest Entity [Line Items]
Borrower remittances	400	8,100
Unamortized discount	89,200	37,700
Consolidated VIE \| On-balance sheet
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	1,422,854	1,211,576
Debt securities of consolidated trusts held by third parties	1,334,014	1,181,948
Consolidated VIE \| Operating Segments \| On-balance sheet \| Agricultural Finance
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	1,422,854	1,211,576
Debt securities of consolidated trusts held by third parties	1,334,014	1,181,948
Consolidated VIE \| Corporate, Non-Segment \| On-balance sheet
Variable Interest Entity [Line Items]
Loans held for investment in consolidated trusts, at amortized cost	0	0
Debt securities of consolidated trusts held by third parties	0	0
Unconsolidated VIE \| On-balance sheet \| Farmer Mac Guaranteed Securities:
Variable Interest Entity [Line Items]
Carrying value	39,131	28,466
Maximum exposure to loss	38,689	31,208
Unconsolidated VIE \| On-balance sheet \| Investment securities:
Variable Interest Entity [Line Items]
Carrying value	3,532,286	3,138,619
Maximum exposure to loss	3,809,871	3,341,427
Unconsolidated VIE \| Off-balance sheet
Variable Interest Entity [Line Items]
Maximum exposure to loss	455,681	500,953
Unconsolidated VIE \| Operating Segments \| On-balance sheet \| Agricultural Finance \| Farmer Mac Guaranteed Securities:
Variable Interest Entity [Line Items]
Carrying value	39,131	28,466
Maximum exposure to loss	38,689	31,208
Unconsolidated VIE \| Operating Segments \| On-balance sheet \| Agricultural Finance \| Investment securities:
Variable Interest Entity [Line Items]
Carrying value	0	0
Maximum exposure to loss	0	0
Unconsolidated VIE \| Operating Segments \| Off-balance sheet \| Agricultural Finance
Variable Interest Entity [Line Items]
Maximum exposure to loss	455,681	500,953
Unconsolidated VIE \| Corporate, Non-Segment \| On-balance sheet \| Farmer Mac Guaranteed Securities:
Variable Interest Entity [Line Items]
Carrying value	0	0
Maximum exposure to loss	0	0
Unconsolidated VIE \| Corporate, Non-Segment \| On-balance sheet \| Investment securities:
Variable Interest Entity [Line Items]
Carrying value	3,532,286	3,138,619
Maximum exposure to loss	3,809,871	3,341,427
Unconsolidated VIE \| Corporate, Non-Segment \| Off-balance sheet
Variable Interest Entity [Line Items]
Maximum exposure to loss	$ 0	$ 0

Amount, after accumulated amortization, of debt discount.

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