Loans - Additional Information (Details)	3 Months Ended		12 Months Ended	63 Months Ended	111 Months Ended
	Aug. 31, 2022 USD ($) loan power_supply_system borrower state distribution_system	Aug. 31, 2021 USD ($)	May 31, 2022 USD ($) loan borrower state distribution_system power_supply_system	Aug. 31, 2022 USD ($) loan borrower power_supply_system distribution_system	Aug. 31, 2022 USD ($) loan borrower power_supply_system distribution_system
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of loans and leases held-for-investment	$ 113,000,000	$ 0
Loans held for sale	0		$ 44,000,000	$ 0	$ 0
Allowance for credit losses for accrued interest receivable	105,000,000		94,000,000	105,000,000	105,000,000
Loans to members	$ 30,687,331,000	28,882,633,000	$ 30,063,386,000	$ 30,687,331,000	$ 30,687,331,000
Number of borrowers | borrower	881		883	881	881
Number of states in which electric and telecommunications borrowers are located | state	49		49
Number of loans outstanding | loan	16,623			16,623	16,623
Increase in nonaccrual loans	$ (10,000,000)
Nonaccrual Loans	217,810,000		$ 227,790,000	$ 217,810,000	$ 217,810,000
Financing receivable, troubled debt restructuring, commitment to lend	$ 0		$ 0	$ 0	$ 0
% of total loans outstanding	100.00%		100.00%	100.00%	100.00%
Financing receivable, allowance for credit loss, writeoff	$ 0	0
Term of loans	35 years
Loans originated prior to 2019	$ 17,998,806,000			$ 17,998,806,000	$ 17,998,806,000
Total loans outstanding	$ 30,674,996,000	$ 28,870,758,000	$ 30,051,354,000	$ 30,674,996,000	$ 30,674,996,000
Percentage of loans originated prior to 2019	59.00%			59.00%	59.00%
Financing receivable, before allowance for credit loss, average remaining maturity	18 years
Number of loans outstanding per borrower | loan	19			19	19
Line of credit commitments as percentage of unadvanced loan commitment	62.00%			62.00%	62.00%
Long-term loan commitments as percentage of unadvanced loan commitment	38.00%			38.00%	38.00%
Brazos Sandy Creek | Brazos Sandy Creek Energy Station
Accounts, Notes, Loans and Financing Receivable [Line Items]
Tenant in common ownership, percentage	25.00%			25.00%	25.00%
Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 113,989,000		113,938,000	$ 113,989,000	$ 113,989,000
Nonperforming TDR loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, troubled debt restructuring	0		0	0	0
Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 217,810,000		$ 227,790,000	$ 217,810,000	$ 217,810,000
Number of borrowers | borrower	3			3	3
% of total loans outstanding	0.71%		0.76%	0.71%	0.71%
Number of borrowers, nonperforming loans | borrower	3		3
Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 492,000,000		$ 494,000,000	$ 492,000,000	$ 492,000,000
% of total loans outstanding	2.00%		2.00%	2.00%	2.00%
Loans originated prior to 2019	$ 157,930,000			$ 157,930,000	$ 157,930,000
Total loans outstanding	491,626,000		$ 494,373,000	491,626,000	491,626,000
Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	274,000,000		267,000,000	274,000,000	274,000,000
Loans originated prior to 2019	25,720,000			25,720,000	25,720,000
Total loans outstanding	273,816,000		266,583,000	273,816,000	273,816,000
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	218,000,000		228,000,000	218,000,000	218,000,000
Loans originated prior to 2019	132,210,000			132,210,000	132,210,000
Total loans outstanding	217,810,000		227,790,000	217,810,000	217,810,000
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	0		0	0	0
Loans originated prior to 2019	0			0	0
Total loans outstanding	0		0	0	0
Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 217,810,000		$ 227,790,000	$ 217,810,000	$ 217,810,000
% of total loans outstanding	96.00%		96.00%	96.00%	96.00%
Total loans outstanding	$ 29,477,492,000		$ 28,872,875,000	$ 29,477,492,000	$ 29,477,492,000
Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans outstanding | loan	2		2	2	2
Total loans outstanding	$ 113,989,000		$ 113,938,000	$ 113,989,000	$ 113,989,000
Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	21,754,000			21,754,000	21,754,000
Total loans outstanding	269,850,000		262,491,000	269,850,000	269,850,000
RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 0		$ 0	$ 0	$ 0
% of total loans outstanding	2.00%		2.00%	2.00%	2.00%
Financing receivable, allowance for credit loss, writeoff				$ 0
Total loans outstanding	$ 469,635,000		$ 467,601,000	469,635,000	$ 469,635,000
RTFC | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	0		0	0	0
RTFC | Loan defaults
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	0			0	0
RTFC | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	3,966,000			3,966,000	3,966,000
Total loans outstanding	$ 3,966,000		$ 4,092,000	$ 3,966,000	$ 3,966,000
Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower	70		68	70	70
Electric utility
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss, writeoff					$ 0
Electric utility | Loan defaults
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 0			$ 0	$ 0
Electric utility | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan commitment term	5 years
Power supply
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower	49		49	49	49
Power supply | Doubtful | One CFC electric power supply borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 104,000,000		$ 114,000,000	$ 104,000,000	$ 104,000,000
Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 217,810,000		$ 227,790,000	$ 217,810,000	$ 217,810,000
% of total loans outstanding	17.00%		17.00%	17.00%	17.00%
Total loans outstanding	$ 5,101,682,000		$ 4,901,770,000	$ 5,101,682,000	$ 5,101,682,000
Power supply | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	113,989,000		113,938,000	113,989,000	113,989,000
Power supply | Parent Company | Brazos electric power cooperative | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	86,000,000		86,000,000	86,000,000	86,000,000
Power supply | Parent Company | Brazos and Brazos Sandy Creek | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	114,000,000		114,000,000	114,000,000	114,000,000
Power supply | Parent Company | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 217,810,000		$ 227,790,000	$ 217,810,000	$ 217,810,000
% of total loans outstanding	0.71%		0.76%	0.71%	0.71%
Financing receivable, number of loans with payments received | loan	1			1	1
Increase (decrease) in finance receivables	$ (10,000,000)
Number of borrowers, nonperforming loans | borrower	3		3
Power supply | Parent Company | Nonperforming financial instruments | Brazos and Brazos Sandy Creek | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 114,000,000		$ 114,000,000	$ 114,000,000	$ 114,000,000
Power supply | Parent Company | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	132,210,000			132,210,000	132,210,000
Total loans outstanding	$ 217,810,000		227,790,000	$ 217,810,000	$ 217,810,000
Power supply | Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower	8			8	8
Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 0		$ 0	$ 0	$ 0
% of total loans outstanding	79.00%		79.00%	79.00%	79.00%
Total loans outstanding	$ 24,244,193,000		$ 23,844,242,000	$ 24,244,193,000	$ 24,244,193,000
Distribution | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	0		0	0	0
Distribution | Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	12,872,000			12,872,000	12,872,000
Total loans outstanding	256,003,000		248,238,000	256,003,000	256,003,000
Distribution | Parent Company | Special mention | CFC electric distribution borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 256,000,000		$ 248,000,000	$ 256,000,000	$ 256,000,000
Distribution | Parent Company | Special mention | CFC electric distribution borrower and subsidiary
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower	1		1	1	1
Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	$ 14,174,077,000		$ 14,111,202,000	$ 14,174,077,000	$ 14,174,077,000
Unadvanced commitments | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	13,344,770,000		13,249,577,000	13,344,770,000	13,344,770,000
Unadvanced commitments | RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	291,419,000		309,724,000	291,419,000	291,419,000
Unadvanced commitments | Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	3,825,651,000		3,835,535,000	3,825,651,000	3,825,651,000
Unadvanced commitments | Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	9,337,695,000		9,230,197,000	9,337,695,000	9,337,695,000
Commitments to extend credit subject to material adverse change clause
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	10,969,000,000		10,908,000,000	10,969,000,000	10,969,000,000
Unadvanced commitments not subject to material adverse change clauses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	3,204,749,000		3,203,000,000	3,204,749,000	3,204,749,000
Nonperforming financial instruments | Power supply | Parent Company | Brazos Sandy Creek
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	28,000,000		28,000,000	28,000,000	28,000,000
Financing Receivable, Unsecured | Power supply | Parent Company | Brazos electric power cooperative | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	65,000,000		65,000,000	65,000,000	65,000,000
Financing Receivable, Secured | Power supply | Parent Company | Brazos electric power cooperative | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 21,000,000		$ 21,000,000	$ 21,000,000	$ 21,000,000
Variable rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of total loans outstanding	3.00%		2.00%	3.00%	3.00%
Total loans outstanding	$ 761,370,000		$ 820,201,000	$ 761,370,000	$ 761,370,000
Variable rate | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan commitment term	5 years
Unadvanced commitments	$ 5,402,527,000		5,357,205,000	5,402,527,000	5,402,527,000
Loans receivable commercial and industrial | Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 5,207,000,000		$ 5,104,000,000	$ 5,207,000,000	$ 5,207,000,000
Concentration risk, percentage	17.00%		17.00%
Loans receivable commercial and industrial | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, number of borrowers | borrower	20		20	20	20
Loans receivable commercial and industrial | Customer concentration risk | Twenty largest borrowers | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 6,356,000,000		$ 6,220,000,000	$ 6,356,000,000	$ 6,356,000,000
Concentration risk, percentage	21.00%		21.00%
Concentration risk, number of borrowers | borrower	20		20	20	20
Loans receivable commercial and industrial | Customer concentration risk | Largest single borrower or controlled group | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	2.00%		2.00%
Loans receivable commercial and industrial | Electric utility | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 30,205,000,000		$ 29,584,000,000	$ 30,205,000,000	$ 30,205,000,000
Loans receivable commercial and industrial | Power supply | Customer concentration risk | Twenty largest borrowers | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, number of borrowers | power_supply_system	8		8	8	8
Loans receivable commercial and industrial | Distribution | Customer concentration risk | Twenty largest borrowers | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, number of borrowers | distribution_system	12		12	12	12
Loans guaranteed by Farmer Mac
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 462,000,000		$ 493,000,000	$ 462,000,000	$ 462,000,000
Financing receivable, before allowance for credit loss, number of defaults | loan	0			0	0
Financing receivable, before allowance for credit loss, number of defaulted loans purchased | loan	0			0	0
Loans guaranteed by Farmer Mac | Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 161,000,000		163,000,000	$ 161,000,000	$ 161,000,000
Loans guaranteed by Farmer Mac | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 241,000,000		$ 316,000,000	241,000,000	241,000,000
Concentration risk, percentage	20.00%		20.00%
Loans guaranteed by rural utilities service
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 129,000,000		$ 131,000,000	$ 129,000,000	$ 129,000,000
Loans and finance receivables | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	98.00%		98.00%
Long-term loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of total loans outstanding	92.00%		92.00%	92.00%	92.00%
Total loans outstanding	$ 28,152,445,000		$ 27,772,573,000	$ 28,152,445,000	$ 28,152,445,000
Long-term loans | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	$ 5,402,527,000		$ 5,357,205,000	$ 5,402,527,000	$ 5,402,527,000
Loans receivable commercial and industrial not covered by Farmer Mac standby repurchase agreement | Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage	16.00%		16.00%