Represents the maximum amount of letters of credit that are available under the credit facility.

No definition available.

Name:	nru_LetterOfCreditMaximumAmountAvailable
Namespace Prefix:	nru_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Number of Active Facilities

+ References

No definition available.

+ Details

Name:	nru_LineOfCreditFacilityNumberOfActiveFacilities
Namespace Prefix:	nru_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Line Of Credit Facility Terminated

+ References

No definition available.

+ Details

Name:	nru_LineOfCreditFacilityTerminated
Namespace Prefix:	nru_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Master Repurchase Agreements, Number of Counterparties

+ References

No definition available.

+ Details

Name:	nru_MasterRepurchaseAgreementsNumberOfCounterparties
Namespace Prefix:	nru_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

Number Of Securities Repurchase Transactions

+ References

No definition available.

+ Details

Name:	nru_NumberOfSecuritiesRepurchaseTransactions
Namespace Prefix:	nru_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	instant

- Definition

For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
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-Topic 275
-SubTopic 10
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-URI http://asc.fasb.org/extlink&oid=99393423&loc=d3e6404-108592

+ Details

Name:	us-gaap_ConcentrationRiskPercentage1
Namespace Prefix:	us-gaap_
Data Type:	dtr-types:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Period of time between issuance and maturity of debt instrument, in PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The total amount of the contingent obligation under letters of credit outstanding as of the reporting date.

+ References

No definition available.

+ Details

Name:	us-gaap_LettersOfCreditOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Fair value of securities pledged as collateral against securities sold under agreement to repurchase.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 20
-Section 55
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226013-175313

+ Details

Name:	us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseFairValueOfCollateral
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Reflects the total carrying amount as of the balance sheet date of debt having initial terms less than one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 852
-SubTopic 10
-Section 55
-Paragraph 10
-URI http://asc.fasb.org/extlink&oid=84165509&loc=d3e56426-112766

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(19)(a))
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(13))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_ShortTermDebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByBenchmarkAxis=us-gaap_DebtMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ConcentrationRiskByTypeAxis=us-gaap_CreditAvailabilityConcentrationRiskMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nru_ThreeYearAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_DebtInstrumentAxis=nru_FiveYearAgreementMember
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Short-Term Borrowings - Additional Information (Details)		6 Months Ended	12 Months Ended
	Jun. 07, 2021 USD ($)	Nov. 30, 2021 USD ($) counterparty facility	May 31, 2021 USD ($)	Nov. 23, 2021 transaction
Short-term Debt [Line Items]
Short-term borrowings		$ 4,746,935,000	$ 4,582,096,000
Master repurchase agreements, number of counterparties \| counterparty		2
Number of securities repurchase transactions \| transaction				2
Debt securities trading, at fair value, pledged as collateral		$ 264,932,000	$ 210,894,000
Number of active facilities \| facility		2
Short-term debt
Short-term Debt [Line Items]
Debt instrument, term (in years)		1 year
Short-term debt \| Debt \| Credit availability concentration risk
Short-term Debt [Line Items]
Concentration risk, percentage		17.00%	17.00%
Securities sold under agreements to repurchase
Short-term Debt [Line Items]
Short-term borrowings		$ 249,291,000	$ 200,115,000
Securities sold under agreements to repurchase \| Debt \| Credit availability concentration risk
Short-term Debt [Line Items]
Concentration risk, percentage		1.00%	1.00%
Revolving credit agreements
Short-term Debt [Line Items]
Short-term borrowings		$ 0	$ 0
Total Commitment		2,600,000,000
Letter of credit, maximum amount available		300,000,000
Letters of Credit Outstanding		$ 3,000,000
Revolving credit agreements \| Three year agreement
Short-term Debt [Line Items]
Debt instrument, term (in years)		3 years
Line of credit facility terminated	$ 70,000,000
Total Commitment		$ 1,245,000,000
Revolving credit agreements \| Five year agreement
Short-term Debt [Line Items]
Debt instrument, term (in years)		5 years
Line of credit facility terminated	$ 55,000,000
Total Commitment		$ 1,355,000,000