Fair Value of Derivatives and Financial Instruments - Changes in Level 3 Assets (Details) - Level 3 $ in Thousands	3 Months Ended
Mar. 31, 2023 USD ($)
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	$ 686,936
Contributions/ Purchases	2,693
Paid in- kind dividends	1,008
Redemptions/ Conversions	(4,971)
Return of capital	0
Realized gain/(loss)	11
Unrealized gain/(loss)	(17,414)
Fair value, ending balance	668,263
CLO
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	6,412
Contributions/ Purchases	0
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	488
Fair value, ending balance	6,900
Common stock
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	234,667
Contributions/ Purchases	0
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	(5,800)
Fair value, ending balance	228,867
Convertible notes
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	50,828
Contributions/ Purchases	0
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	474
Fair value, ending balance	51,302
Life settlement
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	67,711
Contributions/ Purchases	1,266
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	(2,593)
Fair value, ending balance	66,384
LLC interest
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	60,836
Contributions/ Purchases	0
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	(708)
Fair value, ending balance	60,128
LP interest
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	223,141
Contributions/ Purchases	1,427
Paid in- kind dividends	0
Redemptions/ Conversions	0
Return of capital	0
Realized gain/(loss)	0
Unrealized gain/(loss)	(9,439)
Fair value, ending balance	215,129
Senior loan
Investments in and Advances to Affiliates, at Fair Value [Roll Forward]
Fair value, beginning balance	43,341
Contributions/ Purchases	0
Paid in- kind dividends	1,008
Redemptions/ Conversions	(4,971)
Return of capital	0
Realized gain/(loss)	11
Unrealized gain/(loss)	164
Fair value, ending balance	$ 39,553

Fair Value Measurement, Return Of Capital

No definition available.

Name:	nxdt_FairValueMeasurementReturnOfCapital
Namespace Prefix:	nxdt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of realized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

No definition available.

+ Details

Name:	nxdt_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetRealizedGainLossIncludedInEarnings
Namespace Prefix:	nxdt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of unrealized gain (loss) recognized in income from asset measured at fair value on recurring basis using unobservable input (level 3).

+ References

No definition available.

+ Details

Name:	nxdt_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetUnrealizedGainLossIncludedInEarnings
Namespace Prefix:	nxdt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Amount of issuances of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetIssues
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of purchases of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetPurchases
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of settlement of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

+ Details

Name:	us-gaap_FairValueMeasurementWithUnobservableInputsReconciliationRecurringBasisAssetSettlements
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Fair value of financial instrument classified as an asset measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126976982&loc=d3e19207-110258

+ Details

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

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

+ Details

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

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_CLOMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=us-gaap_CommonStockMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_ConvertibleNotesMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_LifeSettlementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_LLCInterestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_LPInterestMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancialInstrumentAxis=nxdt_SeniorLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: