Loans - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended	69 Months Ended	117 Months Ended
	Feb. 28, 2023 USD ($) distribution_system borrower member power_supply_system loan	Feb. 28, 2022 USD ($)	Feb. 28, 2023 USD ($) distribution_system borrower member power_supply_system loan state	Feb. 28, 2022 USD ($)	May 31, 2022 USD ($) borrower distribution_system power_supply_system state member	Feb. 28, 2023 USD ($) distribution_system borrower member power_supply_system loan	Feb. 28, 2023 USD ($) distribution_system borrower member power_supply_system loan	Dec. 20, 2022 USD ($)
Accounts, Notes, Loans and Financing Receivable [Line Items]
Proceeds from sale of loans and leases held-for-investment			$ 192,000,000	$ 64,000,000
Loans held for sale	$ 0		0		$ 44,000,000	$ 0	$ 0
Allowance for credit losses for accrued interest receivable	126,000,000		126,000,000		94,000,000	126,000,000	126,000,000
Loans to members	$ 32,381,829,000	$ 29,520,381,000	$ 32,381,829,000	29,520,381,000	$ 30,063,386,000	$ 32,381,829,000	$ 32,381,829,000
Number of borrowers | borrower	880		880		883	880	880
Number of states in which electric and telecommunications borrowers are located | state			49		49
Increase (decrease) in nonaccrual loans	$ (97,000,000)
Nonaccrual Loans	131,043,000		$ 131,043,000		$ 227,790,000	$ 131,043,000	$ 131,043,000
Financing receivable, troubled debt restructuring, commitment to lend	0		0		$ 0	$ 0	$ 0
Financing receivable, allowance for credit loss, writeoff	$ 0	0	$ 15,069,000	0
% of total loans outstanding	100.00%		100.00%		100.00%	100.00%	100.00%
Net charge-off rate			0.06%
Term of loans			35 years
Loans originated prior to 2019	$ 17,381,470,000		$ 17,381,470,000			$ 17,381,470,000	$ 17,381,470,000
Percentage of loans originated prior to 2019	54.00%		54.00%			54.00%	54.00%
Total loans outstanding	$ 32,369,231,000	$ 29,508,363,000	$ 32,369,231,000	29,508,363,000	$ 30,051,354,000	$ 32,369,231,000	$ 32,369,231,000
Financing receivable, before allowance for credit loss, average remaining maturity			19 years
Line of credit commitments as percentage of unadvanced loan commitment	61.00%		61.00%			61.00%	61.00%
Long-term loan commitments as percentage of unadvanced loan commitment	39.00%		39.00%			39.00%	39.00%
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%	25.00%
Sale of tenant in common ownership, percentage								25.00%
Brazos Sandy Creek | Riesel HoldCo, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of tenant in common ownership								$ 105,000,000
Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 108,167,000		$ 108,167,000		$ 227,790,000	$ 108,167,000	$ 108,167,000
Number of borrowers | borrower	2		2		3	2	2
% of total loans outstanding	0.33%		0.33%		0.76%	0.33%	0.33%
Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 4,347,000		$ 4,347,000		$ 113,938,000	$ 4,347,000	$ 4,347,000
Nonperforming TDR loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, troubled debt restructuring	$ 22,875,000		$ 22,875,000		$ 0	$ 22,875,000	$ 22,875,000
% of total loans outstanding	0.07%		0.07%		0.00%	0.07%	0.07%
Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 337,000,000		$ 337,000,000		$ 494,000,000	$ 337,000,000	$ 337,000,000
% of total loans outstanding	1.00%		1.00%		2.00%	1.00%	1.00%
Increase (decrease) in finance receivables				$ (157,000,000)
Loans originated prior to 2019	$ 132,777,000		$ 132,777,000			$ 132,777,000	$ 132,777,000
Total loans outstanding	337,243,000		337,243,000		$ 494,373,000	337,243,000	337,243,000
Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	206,000,000		206,000,000		267,000,000	206,000,000	206,000,000
Loans originated prior to 2019	24,610,000		24,610,000			24,610,000	24,610,000
Total loans outstanding	206,201,000		206,201,000		266,583,000	206,201,000	206,201,000
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	131,000,000		131,000,000		228,000,000	131,000,000	131,000,000
Loans originated prior to 2019	108,167,000		108,167,000			108,167,000	108,167,000
Total loans outstanding	131,042,000		131,042,000		227,790,000	131,042,000	131,042,000
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	0		0		0	0	0
Loans originated prior to 2019	0		0			0	0
Total loans outstanding	0		0		0	0	0
Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 131,043,000		131,043,000		$ 227,790,000	$ 131,043,000	$ 131,043,000
Financing receivable, allowance for credit loss, writeoff			$ 15,069,000
% of total loans outstanding	95.00%		95.00%		96.00%	95.00%	95.00%
Total loans outstanding	$ 30,899,071,000		$ 30,899,071,000		$ 28,872,875,000	$ 30,899,071,000	$ 30,899,071,000
Parent Company | Riesel HoldCo, LLC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Sale of tenant in common ownership								$ 8,000,000
Tenant in common ownership, credit bid ownership percentage								7.41%
Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans outstanding | member	1		1		2	1	1
Total loans outstanding	$ 4,347,000		$ 4,347,000		$ 113,938,000	$ 4,347,000	$ 4,347,000
Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	20,893,000		20,893,000			20,893,000	20,893,000
Total loans outstanding	202,484,000		202,484,000		262,491,000	202,484,000	202,484,000
RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 0		0		$ 0	0	$ 0
Financing receivable, allowance for credit loss, writeoff			$ 0			$ 0
% of total loans outstanding	2.00%		2.00%		2.00%	2.00%	2.00%
Total loans outstanding	$ 481,789,000		$ 481,789,000		$ 467,601,000	$ 481,789,000	$ 481,789,000
RTFC | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	0		0		0	0	0
RTFC | Loan defaults
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	0		0			0	0
RTFC | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	3,717,000		3,717,000			3,717,000	3,717,000
Total loans outstanding	3,717,000		3,717,000		$ 4,092,000	3,717,000	3,717,000
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	$ 0
Power supply
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower	51		51		49	51	51
Power supply | One CFC electric power supply borrower | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 104,000,000		$ 104,000,000		$ 114,000,000	$ 104,000,000	$ 104,000,000
Power supply | Brazos and Brazos Sandy Creek | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, allowance for credit loss, writeoff			15,000,000
Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 131,043,000		131,043,000		$ 227,790,000	$ 131,043,000	$ 131,043,000
Financing receivable, allowance for credit loss, writeoff			$ 15,069,000
% of total loans outstanding	16.00%		16.00%		17.00%	16.00%	16.00%
Total loans outstanding	$ 5,318,565,000		$ 5,318,565,000		$ 4,901,770,000	$ 5,318,565,000	$ 5,318,565,000
Power supply | Parent Company | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 108,167,000		$ 108,167,000		$ 227,790,000	$ 108,167,000	$ 108,167,000
% of total loans outstanding	0.33%		0.33%		0.76%	0.33%	0.33%
Increase (decrease) in finance receivables			$ (120,000,000)
Power supply | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	$ 4,347,000		4,347,000		$ 113,938,000	$ 4,347,000	$ 4,347,000
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
Power supply | Parent Company | Brazos and Brazos Sandy Creek | Total Past Due | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	27,000,000		27,000,000			27,000,000	27,000,000
Power supply | Parent Company | Brazos Sandy Creek | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	4,000,000		4,000,000		28,000,000	4,000,000	4,000,000
Power supply | Parent Company | Nonperforming TDR loans | Brazos electric power cooperative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Financing receivable, troubled debt restructuring	23,000,000		23,000,000			23,000,000	23,000,000
Power supply | Parent Company | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	108,167,000		108,167,000			108,167,000	108,167,000
Total loans outstanding	131,042,000		131,042,000		227,790,000	131,042,000	131,042,000
Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Nonaccrual Loans	$ 0		0		$ 0	$ 0	$ 0
Financing receivable, allowance for credit loss, writeoff			$ 0
% of total loans outstanding	79.00%		79.00%		79.00%	79.00%	79.00%
Total loans outstanding	$ 25,424,628,000		$ 25,424,628,000		$ 23,844,242,000	$ 25,424,628,000	$ 25,424,628,000
Distribution | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans outstanding	0		0		0	0	0
Distribution | Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans originated prior to 2019	12,395,000		12,395,000			12,395,000	12,395,000
Total loans outstanding	189,142,000		189,142,000		248,238,000	189,142,000	189,142,000
Distribution | Parent Company | Special mention | CFC electric distribution borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 189,000,000		$ 189,000,000		$ 248,000,000	$ 189,000,000	$ 189,000,000
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	1
Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	$ 14,320,278,000		$ 14,320,278,000		$ 14,111,202,000	$ 14,320,278,000	$ 14,320,278,000
Unadvanced commitments | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	13,369,053,000		13,369,053,000		13,249,577,000	13,369,053,000	13,369,053,000
Unadvanced commitments | RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	345,104,000		345,104,000		309,724,000	345,104,000	345,104,000
Unadvanced commitments | Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	3,884,174,000		3,884,174,000		3,835,535,000	3,884,174,000	3,884,174,000
Unadvanced commitments | Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	9,332,479,000		9,332,479,000		9,230,197,000	9,332,479,000	9,332,479,000
Commitments to extend credit subject to material adverse change clause
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	11,188,000,000		11,188,000,000		10,908,000,000	11,188,000,000	11,188,000,000
Unadvanced commitments not subject to material adverse change clauses
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	$ 3,131,762,000		$ 3,131,762,000		$ 3,203,000,000	$ 3,131,762,000	$ 3,131,762,000
Variable rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
% of total loans outstanding	3.00%		3.00%		2.00%	3.00%	3.00%
Total loans outstanding	$ 915,095,000		$ 915,095,000		$ 820,201,000	$ 915,095,000	$ 915,095,000
Variable rate | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan commitment term			5 years
Unadvanced commitments	5,643,107,000		$ 5,643,107,000		5,357,205,000	5,643,107,000	5,643,107,000
Loans receivable commercial and industrial | Customer concentration risk | Twenty largest borrowers | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 6,558,000,000		$ 6,558,000,000		$ 6,220,000,000	$ 6,558,000,000	$ 6,558,000,000
Concentration risk, percentage			20.00%		21.00%
Concentration risk, number of borrowers | borrower	20		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			1.00%		1.00%
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	20
Loans receivable commercial and industrial | Electric utility | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 31,887,000,000		$ 31,887,000,000		$ 29,584,000,000	$ 31,887,000,000	$ 31,887,000,000
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	10		10		8	10	10
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	10		10		12	10	10
Loans guaranteed by Farmer Mac
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 443,000,000		$ 443,000,000		$ 493,000,000	$ 443,000,000	$ 443,000,000
Financing receivable, before allowance for credit loss, number of defaults | loan	0		0			0	0
Financing receivable, before allowance for credit loss, number of defaulted loans purchased | loan	0		0			0	0
Loans guaranteed by Farmer Mac | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 270,000,000		$ 270,000,000		$ 316,000,000	$ 270,000,000	$ 270,000,000
Concentration risk, percentage			19.00%		20.00%
Loans guaranteed by rural utilities service
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans to members	$ 125,000,000		$ 125,000,000		$ 131,000,000	$ 125,000,000	$ 125,000,000
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	89.00%		89.00%		92.00%	89.00%	89.00%
Total loans outstanding	$ 28,954,903,000		$ 28,954,903,000		$ 27,772,573,000	$ 28,954,903,000	$ 28,954,903,000
Long-term loans | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments	$ 5,643,107,000		$ 5,643,107,000		$ 5,357,205,000	$ 5,643,107,000	$ 5,643,107,000