Loans - Additional Information (Details)	3 Months Ended		9 Months Ended		12 Months Ended	57 Months Ended	105 Months Ended
	Nov. 30, 2021 USD ($) borrower	Aug. 31, 2021 borrower	Feb. 28, 2022 USD ($) loan borrower state power_supply_system distribution_system	Feb. 28, 2021 USD ($)	May 31, 2021 USD ($) loan borrower power_supply_system distribution_system state	Feb. 28, 2022 USD ($) loan borrower power_supply_system distribution_system	Feb. 28, 2022 USD ($) 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			$ 64,000,000	$ 126,000,000
Allowance for credit losses for accrued interest receivable			96,000,000		$ 93,000,000	$ 96,000,000	$ 96,000,000
Outstanding Amount			$ 29,508,363,000	28,315,671,000	$ 28,415,107,000	$ 29,508,363,000	$ 29,508,363,000
Number of borrowers | borrower			885		892	885	885
Number of states in which electric and telecommunications borrowers are located | state			49		49
Number of loans outstanding | loan			16,572			16,572	16,572
Increase in nonaccrual loans				(30,000,000)
Nonaccrual Loans			$ 207,254,000		$ 237,497,000	$ 207,254,000	$ 207,254,000
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 2018			$ 16,825,257,000			$ 16,825,257,000	$ 16,825,257,000
Percentage of loans originated prior to 2018			57.00%			57.00%	57.00%
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			63.00%			63.00%	63.00%
Long-term loan commitments as percentage of unadvanced loan commitment			37.00%			37.00%	37.00%
Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 85,549,000		$ 84,996,000	$ 85,549,000	$ 85,549,000
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]
Outstanding Amount			$ 207,254,000		$ 237,497,000	$ 207,254,000	$ 207,254,000
Number of borrowers | borrower			2		4	2	2
% of total loans outstanding			0.70%		0.84%	0.70%	0.70%
Number of borrowers, nonperforming loans | borrower		4	2
Nonperforming financial instruments | RTFC Borrower One
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in finance receivables	$ (9,000,000)
Nonperforming financial instruments | RTFC Borrower Two
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in finance receivables	$ (9,000,000)
Criticized
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 504,373,000		$ 885,865,000	$ 504,373,000	$ 504,373,000
% of total loans outstanding			2.00%		3.00%	2.00%	2.00%
Loans originated prior to 2018			$ 172,306,000			$ 172,306,000	$ 172,306,000
Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			297,119,000		$ 269,387,000	297,119,000	297,119,000
Loans originated prior to 2018			50,601,000			50,601,000	50,601,000
Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			207,254,000		237,497,000	207,254,000	207,254,000
Loans originated prior to 2018			121,705,000			121,705,000	121,705,000
Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			0		378,981,000	0	0
Loans originated prior to 2018			0			0	0
Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			28,320,476,000		27,287,856,000	28,320,476,000	28,320,476,000
Nonaccrual Loans			$ 207,254,000		$ 228,312,000	$ 207,254,000	$ 207,254,000
% of total loans outstanding			96.00%		96.00%	96.00%	96.00%
Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 85,549,000		$ 84,996,000	$ 85,549,000	$ 85,549,000
Parent Company | Brazos electric power cooperative | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of loans outstanding | loan			1		1	1	1
Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 292,902,000		$ 264,795,000	$ 292,902,000	$ 292,902,000
Loans originated prior to 2018			46,384,000			46,384,000	46,384,000
Parent Company | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			207,254,000		228,312,000	207,254,000	207,254,000
Loans originated prior to 2018			121,705,000			121,705,000	121,705,000
Parent Company | Substandard | Rayburn country electric cooperative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			207,000,000		379,000,000	207,000,000	207,000,000
RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			457,740,000		420,383,000	457,740,000	457,740,000
Nonaccrual Loans			$ 0		$ 9,185,000	$ 0	$ 0
% of total loans outstanding			2.00%		1.00%	2.00%	2.00%
Financing receivable, allowance for credit loss, writeoff						$ 0
RTFC | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 0		$ 0	0	$ 0
RTFC | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 0		$ 9,185,000	$ 0	$ 0
Number of borrowers | borrower					2
% of total loans outstanding			0.00%		0.03%	0.00%	0.00%
Number of borrowers, nonperforming loans | borrower	2	2	0
RTFC | Loan defaults
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 0			$ 0	$ 0
RTFC | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			4,217,000		$ 4,592,000	4,217,000	4,217,000
Loans originated prior to 2018			4,217,000			4,217,000	4,217,000
RTFC | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			0		$ 9,185,000	0	0
Loans originated prior to 2018			$ 0			$ 0	$ 0
Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of borrowers | borrower			67		67	67	67
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]
Outstanding Amount			$ 0			$ 0	0
Electric utility | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan commitment term			5 years
Power supply | Nonperforming financial instruments | One CFC electric power supply borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in finance receivables			$ (22,000,000)
Power supply | Doubtful | One CFC electric power supply borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			121,000,000		$ 143,000,000	121,000,000	121,000,000
Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			4,992,073,000		5,154,312,000	4,992,073,000	4,992,073,000
Nonaccrual Loans			$ 207,254,000		$ 228,312,000	$ 207,254,000	$ 207,254,000
% of total loans outstanding			17.00%		18.00%	17.00%	17.00%
Power supply | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 85,549,000		$ 84,996,000	$ 85,549,000	$ 85,549,000
Power supply | Parent Company | Brazos electric power cooperative | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			86,000,000		85,000,000	86,000,000	86,000,000
Power supply | Parent Company | Nonperforming financial instruments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 207,254,000		$ 228,312,000	$ 207,254,000	$ 207,254,000
% of total loans outstanding			0.70%		0.81%	0.70%	0.70%
Number of borrowers, nonperforming loans | borrower		2	2
Power supply | Parent Company | Criticized | Brazos electric power cooperative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 86,000,000		$ 85,000,000	$ 86,000,000	$ 86,000,000
Power supply | Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			28,389,000		29,611,000	28,389,000	28,389,000
Loans originated prior to 2018			28,389,000			28,389,000	28,389,000
Power supply | Parent Company | Doubtful
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			207,254,000		228,312,000	207,254,000	207,254,000
Loans originated prior to 2018			121,705,000			121,705,000	121,705,000
Power supply | Parent Company | Substandard
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			0		378,981,000	0	0
Loans originated prior to 2018			0			0	0
Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			23,225,751,000		22,027,423,000	23,225,751,000	23,225,751,000
Nonaccrual Loans			$ 0		$ 0	$ 0	$ 0
% of total loans outstanding			79.00%		78.00%	79.00%	79.00%
Distribution | Parent Company | Total Past Due
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 0		$ 0	$ 0	$ 0
Distribution | Parent Company | Special mention
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			250,072,000		219,324,000	250,072,000	250,072,000
Loans originated prior to 2018			12,446,000			12,446,000	12,446,000
Distribution | Parent Company | Special mention | CFC electric distribution borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 250,000,000		219,000,000	$ 250,000,000	$ 250,000,000
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
RTFC | Nonperforming financial instruments | RTFC Borrower
Accounts, Notes, Loans and Financing Receivable [Line Items]
Increase (decrease) in finance receivables			$ (30,000,000)
Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			14,161,226,000		14,357,039,000	$ 14,161,226,000	$ 14,161,226,000
Unadvanced commitments | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			13,291,118,000		13,519,108,000	13,291,118,000	13,291,118,000
Unadvanced commitments | RTFC
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			323,008,000		286,806,000	323,008,000	323,008,000
Unadvanced commitments | Power supply | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			3,877,775,000		3,970,698,000	3,877,775,000	3,877,775,000
Unadvanced commitments | Distribution | Parent Company
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			9,235,009,000		9,387,070,000	9,235,009,000	9,235,009,000
Commitments to extend credit subject to material adverse change clause
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			10,969,000,000		11,312,000,000	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			3,192,262,000		3,045,000,000	3,192,262,000	3,192,262,000
Nonperforming financial instruments | Power supply | Parent Company | Brazos electric power cooperative
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount					85,000,000
Variable rate
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 720,027,000		$ 658,579,000	$ 720,027,000	$ 720,027,000
% of total loans outstanding			2.00%		2.00%	2.00%	2.00%
Variable rate | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loan commitment term			5 years
Unadvanced commitments			$ 5,230,253,000		$ 5,771,813,000	$ 5,230,253,000	$ 5,230,253,000
Loans receivable commercial and industrial | Geographic concentration risk | TEXAS | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 4,955,000,000		$ 4,878,000,000	$ 4,955,000,000	$ 4,955,000,000
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]
Outstanding Amount			$ 6,213,000,000		$ 6,182,000,000	$ 6,213,000,000	$ 6,213,000,000
Concentration risk, percentage			21.00%		22.00%
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]
Outstanding Amount			$ 29,051,000,000		$ 27,995,000,000	$ 29,051,000,000	$ 29,051,000,000
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		10	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		10	12	12
Loans guaranteed by Farmer Mac
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 471,000,000		$ 512,000,000	$ 471,000,000	$ 471,000,000
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]
Outstanding Amount			$ 165,000,000		172,000,000	$ 165,000,000	$ 165,000,000
Loans guaranteed by Farmer Mac | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 290,000,000		$ 309,000,000	290,000,000	290,000,000
Concentration risk, percentage			20.00%		21.00%
Loans guaranteed by rural utilities service
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 133,000,000		$ 139,000,000	133,000,000	133,000,000
Loans and finance receivables | Credit concentration risk | Accounts receivable
Accounts, Notes, Loans and Financing Receivable [Line Items]
Concentration risk, percentage			98.00%		99.00%
Long-term loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Outstanding Amount			$ 27,172,369,000		$ 26,173,345,000	$ 27,172,369,000	$ 27,172,369,000
% of total loans outstanding			92.00%		92.00%	92.00%	92.00%
Long-term loans | Unadvanced commitments
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unadvanced commitments			$ 5,230,253,000		$ 5,771,813,000	$ 5,230,253,000	$ 5,230,253,000
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%