Financial Derivatives - Schedule of Net Income/(Expense) Recognized (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Derivative Instruments, Gain (Loss) [Line Items]
Investments and cash equivalents	$ 79,947	$ 21,581	$ 209,429	$ 38,497
Interest Income Farmer Mac Guaranteed Securities and USDA Securities	161,351	74,695	442,649	169,231
Interest Income Loans	140,513	97,514	388,837	241,393
Total interest expense	(294,168)	(125,937)	(795,537)	(251,816)
Gains on financial derivatives	2,671	772	4,763	21,551
Total	90,314	68,625	250,141	218,856
Interest expense on interest rate swaps	9,505	4,192	20,731	33,272
Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(265,777)	(159,661)	(313,047)	(488,481)
Gains/(losses) on fair value hedging relationships	3,210	(625)	(1,796)	5,953
Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(14)	(15)	(41)	(43)
Interest settlements reclassified from AOCI into net income on derivatives	5,569	1,072	15,051	(2,094)
Recognized on hedged items	(8,287)	(4,046)	(23,325)	(6,654)
Expense recognized on cash flow hedges	(2,732)	(2,989)	(8,315)	(8,791)
Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(20,127)	19,974	(38,049)	76,840
Premium/discount amortization recognized on hedged items	(109)	(608)	(738)	(2,294)
No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	2,671	772	4,763	21,551
Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(41,944)	(52,308)	(46,485)	(108,002)
Gains/(losses) on fair value hedging relationships	107	(2,935)	(763)	(1,067)
Interest Income Investments and Cash Equivalents | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Expense recognized on cash flow hedges	0	0	0	0
Interest Income Investments and Cash Equivalents | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	9,006	4,617	23,865	10,433
Premium/discount amortization recognized on hedged items	623	(59)	1,399	(816)
Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest Income Farmer Mac Guaranteed Securities and USDA Securities | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(107,965)	(204,765)	(116,591)	(564,679)
Gains/(losses) on fair value hedging relationships	2,231	(2,901)	676	(782)
Interest Income Farmer Mac Guaranteed Securities and USDA Securities | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Expense recognized on cash flow hedges	0	0	0	0
Interest Income Farmer Mac Guaranteed Securities and USDA Securities | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	46,303	35,763	133,995	102,123
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest Income Farmer Mac Guaranteed Securities and USDA Securities | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(105,403)	(100,490)	(97,827)	(337,443)
Gains/(losses) on fair value hedging relationships	1,862	5,193	(481)	9,591
Interest Income Loans | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Expense recognized on cash flow hedges	0	0	0	0
Interest Income Loans | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	16,089	14,857	47,144	41,146
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(10,465)	197,902	(52,144)	521,643
Gains/(losses) on fair value hedging relationships	(990)	18	(1,228)	(1,789)
Total Interest Expense | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(14)	(15)	(41)	(43)
Interest settlements reclassified from AOCI into net income on derivatives	5,569	1,072	15,051	(2,094)
Recognized on hedged items	(8,287)	(4,046)	(23,325)	(6,654)
Expense recognized on cash flow hedges	(2,732)	(2,989)	(8,315)	(8,791)
Total Interest Expense | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(91,525)	(35,263)	(243,053)	(76,862)
Premium/discount amortization recognized on hedged items	(732)	(549)	(2,137)	(1,478)
Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Gains on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	0	0	0	0
Gains/(losses) on fair value hedging relationships	0	0	0	0
Gains on financial derivatives | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0	0	0
Recognized on hedged items	0	0	0	0
Expense recognized on cash flow hedges	0	0	0	0
Gains on financial derivatives | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	0	0	0	0
Premium/discount amortization recognized on hedged items	0	0	0	0
Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	2,671	772	4,763	21,551
Interest Rate Swap | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(24,907)	(20,235)	(82,758)	(52,622)
Income/(expense) related to interest settlements on fair value hedging relationships	(45,143)	(869)	(121,545)	21,924
Recognized on derivatives	268,987	159,036	311,251	494,434
Interest Rate Swap | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	2,772	5,054	5,263	10,954
Interest expense on interest rate swaps	(805)	(2,613)	(3,999)	(5,496)
Interest Rate Swap | Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	9,950	957	24,952	(1,536)
Income/(expense) related to interest settlements on fair value hedging relationships	19,579	5,515	50,216	8,081
Recognized on derivatives	42,051	49,373	45,722	106,935
Interest Rate Swap | Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest expense on interest rate swaps	0	0	0	0
Interest Rate Swap | Interest Income Farmer Mac Guaranteed Securities and USDA Securities | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	40,114	(350)	104,023	(37,687)
Income/(expense) related to interest settlements on fair value hedging relationships	86,417	35,413	238,018	64,436
Recognized on derivatives	110,196	201,864	117,267	563,897
Interest Rate Swap | Interest Income Farmer Mac Guaranteed Securities and USDA Securities | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest expense on interest rate swaps	0	0	0	0
Interest Rate Swap | Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	17,692	1,837	46,625	(9,568)
Income/(expense) related to interest settlements on fair value hedging relationships	33,781	16,694	93,769	31,578
Recognized on derivatives	107,265	105,683	97,346	347,034
Interest Rate Swap | Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest expense on interest rate swaps	0	0	0	0
Interest Rate Swap | Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(92,663)	(22,679)	(258,358)	(3,831)
Income/(expense) related to interest settlements on fair value hedging relationships	(184,920)	(58,491)	(503,548)	(82,171)
Recognized on derivatives	9,475	(197,884)	50,916	(523,432)
Interest Rate Swap | Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Interest expense on interest rate swaps	0	0	0	0
Interest Rate Swap | Gains on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	0	0	0	0
Income/(expense) related to interest settlements on fair value hedging relationships	0	0	0	0
Recognized on derivatives	0	0	0	0
Interest Rate Swap | Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	2,772	5,054	5,263	10,954
Interest expense on interest rate swaps	(805)	(2,613)	(3,999)	(5,496)
Treasury futures | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	704	(1,669)	3,499	16,093
Treasury futures | Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Treasury futures | Interest Income Farmer Mac Guaranteed Securities and USDA Securities | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Treasury futures | Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Treasury futures | Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0	0	0
Treasury futures | Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	$ 704	$ (1,669)	$ 3,499	$ 16,093