Summary of Significant Accounting Policies - Consolidation of Variable Interest Entities (Details) - USD ($) $ in Thousands	Jun. 30, 2022	Dec. 31, 2021
Variable Interest Entity [Line Items]
Loans held for investment, at amortized cost	$ 8,911,475	$ 8,314,096
Debt securities of consolidated trusts held by third parties	23,838,159	22,758,533
Farmer Mac Guaranteed Securities
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	6,450,212	6,328,559
Investment securities:
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	4,246,012	3,836,391
On-Balance Sheet: | Consolidated VIE
Variable Interest Entity [Line Items]
Loans held for investment, at amortized cost	834,941	948,623
Debt securities of consolidated trusts held by third parties	866,107	981,379
On-Balance Sheet: | Farmer Mac Guaranteed Securities | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	31,425	42,298
Maximum exposure to loss	33,200	42,155
On-Balance Sheet: | Investment securities: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	2,720,813	2,258,219
Maximum exposure to loss	2,813,424	2,246,272
Off-Balance Sheet: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Maximum exposure to loss	523,580	578,358
Agricultural Finance
Variable Interest Entity [Line Items]
Loans held for investment, at amortized cost	7,198,862	6,846,993
Borrower remittances	31,200	32,800
Operating Segments | Agricultural Finance | On-Balance Sheet: | Consolidated VIE
Variable Interest Entity [Line Items]
Loans held for investment, at amortized cost	834,941	948,623
Debt securities of consolidated trusts held by third parties	866,107	981,379
Operating Segments | Agricultural Finance | On-Balance Sheet: | Farmer Mac Guaranteed Securities | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	31,425	42,298
Maximum exposure to loss	33,200	42,155
Operating Segments | Agricultural Finance | On-Balance Sheet: | Investment securities: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	0	0
Maximum exposure to loss	0	0
Operating Segments | Agricultural Finance | Off-Balance Sheet: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Maximum exposure to loss	523,580	578,358
Corporate | On-Balance Sheet: | Consolidated VIE
Variable Interest Entity [Line Items]
Loans held for investment, at amortized cost	0	0
Debt securities of consolidated trusts held by third parties	0	0
Corporate | On-Balance Sheet: | Farmer Mac Guaranteed Securities | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	0	0
Maximum exposure to loss	0	0
Corporate | On-Balance Sheet: | Investment securities: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Available-for-sale, at fair value	2,720,813	2,258,219
Maximum exposure to loss	2,813,424	2,246,272
Corporate | Off-Balance Sheet: | Unconsolidated VIE
Variable Interest Entity [Line Items]
Maximum exposure to loss	$ 0	$ 0