Financial Derivatives - Schedule of Net Income/(Expense) Recognized (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Derivative Instruments, Gain (Loss) [Line Items]
Investments and cash equivalents	$ 5,716	$ 5,529
Interest Income Farmer Mac Guaranteed Securities and USDA Securities	39,257	42,404
Interest Income Loans	67,247	59,494
Total interest expense	(50,345)	(54,176)
Gains on financial derivatives	16,074	4,293
Total	77,949	52,015
Expense recognized on cash flow hedges	20,491	8,837
Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(136,167)	(284,049)
Gains/(losses) on fair value hedging relationships	2,364	345
Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(13)	(7)
Interest settlements reclassified from AOCI into net income on derivatives	(2,011)	(1,746)
Recognized on hedged items	(787)	(655)
Expense recognized on cash flow hedges	(2,811)	(2,408)
Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	28,988	30,454
Premium/discount amortization recognized on hedged items	(854)	(221)
No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	16,074	4,293
Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(32,726)
Gains/(losses) on fair value hedging relationships	699
Interest Income Investments and Cash Equivalents | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0
Interest settlements reclassified from AOCI into net income on derivatives	0
Recognized on hedged items	0
Expense recognized on cash flow hedges	0
Interest Income Investments and Cash Equivalents | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	2,597
Premium/discount amortization recognized on hedged items	414
Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0
Interest Income Farmer Mac Guaranteed Securities and USDA Securities | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(210,648)	(168,801)
Gains/(losses) on fair value hedging relationships	(460)	(723)
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
Interest settlements reclassified from AOCI into net income on derivatives	0	0
Recognized on hedged items	0	0
Expense recognized on cash flow hedges	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	31,929	30,775
Premium/discount amortization recognized on hedged items	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
Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(129,607)	(144,749)
Gains/(losses) on fair value hedging relationships	2,325	1,022
Interest Income Loans | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0
Recognized on hedged items	0	0
Expense recognized on cash flow hedges	0	0
Interest Income Loans | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	12,619	11,487
Premium/discount amortization recognized on hedged items	0	0
Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	236,814	29,501
Gains/(losses) on fair value hedging relationships	(200)	46
Total Interest Expense | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	(13)	(7)
Interest settlements reclassified from AOCI into net income on derivatives	(2,011)	(1,746)
Recognized on hedged items	(787)	(655)
Expense recognized on cash flow hedges	(2,811)	(2,408)
Total Interest Expense | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	(18,157)	(11,808)
Premium/discount amortization recognized on hedged items	(440)	(221)
Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Gains on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	0	0
Gains/(losses) on fair value hedging relationships	0	0
Gains on financial derivatives | Cash flow hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Premium/discount amortization recognized on hedged items	0	0
Interest settlements reclassified from AOCI into net income on derivatives	0	0
Recognized on hedged items	0	0
Expense recognized on cash flow hedges	0	0
Gains on financial derivatives | Designated as hedge | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on hedged items	0	0
Premium/discount amortization recognized on hedged items	0	0
Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	16,074	4,293
Interest Rate Swap | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(15,874)	(18,528)
Income/(expense) related to interest settlements on fair value hedging relationships	12,260	11,705
Recognized on derivatives	138,531	284,394
Interest Rate Swap | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	703	1,470
Expense recognized on cash flow hedges	(927)	2,223
Interest Rate Swap | Interest Income Investments and Cash Equivalents | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(1,484)
Income/(expense) related to interest settlements on fair value hedging relationships	699
Recognized on derivatives	33,425
Interest Rate Swap | Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0
Expense recognized on cash flow hedges	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	(21,644)	(21,437)
Income/(expense) related to interest settlements on fair value hedging relationships	10,285	9,338
Recognized on derivatives	210,188	168,078
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
Expense recognized on cash flow hedges	0	0
Interest Rate Swap | Interest Income Loans | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	(6,946)	(6,572)
Income/(expense) related to interest settlements on fair value hedging relationships	5,673	4,915
Recognized on derivatives	131,932	145,771
Interest Rate Swap | Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Expense recognized on cash flow hedges	0	0
Interest Rate Swap | Total Interest Expense | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	14,200	9,481
Income/(expense) related to interest settlements on fair value hedging relationships	(4,397)	(2,548)
Recognized on derivatives	(237,014)	(29,455)
Interest Rate Swap | Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Expense recognized on cash flow hedges	0	0
Interest Rate Swap | Gains on financial derivatives | Fair value hedges:
Derivative Instruments, Gain (Loss) [Line Items]
Recognized on derivatives	0	0
Income/(expense) related to interest settlements on fair value hedging relationships	0	0
Recognized on derivatives	0	0
Interest Rate Swap | Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	703	1,470
Expense recognized on cash flow hedges	(927)	2,223
Treasury futures | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	16,298	600
Treasury futures | Interest Income Investments and Cash Equivalents | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	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
Treasury futures | Interest Income Loans | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Treasury futures | Total Interest Expense | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	0	0
Treasury futures | Gains on financial derivatives | No hedge designation
Derivative Instruments, Gain (Loss) [Line Items]
Gains on financial derivatives	$ 16,298	$ 600