Business Combination, Contingent Consideration Arrangements, Number of Components

No definition available.

Name:	nymt_BusinessCombinationContingentConsiderationArrangementsNumberofComponents
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Period Type:	duration

- Definition

Capital Managed by Third Party

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Contingent Consideration, Term

+ References

No definition available.

+ Details

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- Definition

Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners prior to Acquisition

+ References

No definition available.

+ Details

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- Definition

Reimbursement to Previous Beneficial Owner for Purchase of Company Shares

+ References

No definition available.

+ Details

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- 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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Period Type:	duration

- Definition

In a business combination in which the amount of net identifiable assets acquired and liabilities assumed exceeds the aggregate consideration transferred or to be transferred (as defined), this element represents the amount of gain recognized by the entity.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 25
-Paragraph 3
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+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Fair value at acquisition-date of the assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interests issued by the acquirer, including but not limited to, instruments or interests issued or issuable in consideration for the business combination.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (g)
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+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Amount of liability recognized arising from contingent consideration in a business combination, expected to be settled within one year or the normal operating cycle, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-Paragraph 1
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

This element represents the amount of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

+ References

+ Details

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

- Definition

This element represents the amount of any measurement period adjustment (as defined) realized during the reporting period to intangibles acquired in connection with a business combination for which the initial accounting was incomplete.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 20
-Section 50
-Paragraph 4A
-Subparagraph (c)
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+ Details

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Balance Type:	debit
Period Type:	duration

- Definition

Amount of intangible assets, excluding goodwill, acquired at the acquisition date.

+ References

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-SubTopic 20
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-Paragraph 1
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+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value at acquisition-date of the equity interest in the acquiree held by the acquirer, immediately before the acquisition date for businesses combined in stages.

+ References

+ Details

Name:	us-gaap_BusinessCombinationStepAcquisitionEquityInterestInAcquireeFairValue1
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Percentage of equity in the acquiree held by the acquirer immediately before the acquisition date in a business combination.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

In a business combination achieved in stages, this element represents the amount of net gain (loss) recognized by the entity as a result of remeasuring to fair value the equity interest in the acquiree it held before the business combination.

+ References

+ Details

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Balance Type:	credit
Period Type:	duration

- Definition

Useful life of finite-lived intangible assets, 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_FiniteLivedIntangibleAssetUsefulLife
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Balance Type:	na
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
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-Paragraph 1
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+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant

- Definition

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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+ Details

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Balance Type:	debit
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- Definition

Amount of increase (decrease) from adjustments after acquisition date under purchase accounting of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Balance Type:	debit
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- Definition

Cash outflow representing an adjustment to the purchase price of a previous acquisition.

+ References

No definition available.

+ Details

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- Definition

Percentage of subsidiary's or equity method investee's stock owned by parent immediately after all stock transactions.

+ References

No definition available.

+ Details

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- Details

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Balance Type:
Period Type:

- Details

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- Details

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Period Type:

- Details

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Business Combinations - Narrative (Details)					8 Months Ended	9 Months Ended		12 Months Ended
Business Combinations - Narrative (Details)	Oct. 01, 2016 USD ($)	Jul. 15, 2016 USD ($)	Jun. 10, 2016 USD ($)	May 16, 2016 USD ($) component	Dec. 31, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	May 17, 2016	May 15, 2016	Mar. 31, 2016 USD ($)
Business Acquisition [Line Items]
Equity interest in acquiree, percentage									80.00%
Capital											$ 371,500,000
Gain on remeasurement of existing membership interest in businesses acquired						$ 0	$ 5,052,000
Goodwill					$ 25,222,000	25,222,000		$ 25,222,000
Goodwill impairment	$ 0
Gain on bargain purchase on businesses acquired						$ 0	$ 65,000
Revenue of acquiree since acquisition date								5,300,000
Minimum
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life						6 months
Maximum
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life						10 years
RiverBanc
Business Acquisition [Line Items]
Ownership percentage by noncontrolling owners prior to acquisition										59.40%
RBMI
Business Acquisition [Line Items]
Ownership percentage by noncontrolling owners prior to acquisition										5.47%
RBDHC
Business Acquisition [Line Items]
Ownership percentage by noncontrolling owners prior to acquisition										6.25%
RiverBanc, RBMI, and RBDHC
Business Acquisition [Line Items]
Subsidiary cumulative percentage ownership after all transactions				100.00%
Total consideration transferred				$ 53,481,000
Fair value of previously held membership interests				$ 20,608,000
Contingent consideration, number of components \| component				2
Payments for previous acquisition		$ 20,000
Intangible assets				$ 3,490,000
RiverBanc, RBMI, and RBDHC \| Other Income
Business Acquisition [Line Items]
Gain on remeasurement of existing membership interest in businesses acquired								5,000,000
RiverBanc, RBMI, and RBDHC \| Cash Holdback
Business Acquisition [Line Items]
Payments for previous acquisition			$ 3,000,000
Contingent consideration				3,000,000
Reimbursement to previous beneficial owner for purchase of company shares				$ 3,000,000
Contingent consideration term				90 days
RiverBanc, RBMI, and RBDHC \| Severance Holdback
Business Acquisition [Line Items]
Payments for previous acquisition		800,000
Contingent consideration				$ 800,000
RiverBanc, RBMI, and RBDHC \| RiverBanc
Business Acquisition [Line Items]
Equity interest in acquiree, percentage										20.00%
RiverBanc, RBMI, and RBDHC \| RBMI
Business Acquisition [Line Items]
Equity interest in acquiree, percentage										67.19%
RiverBanc, RBMI, and RBDHC \| RBDHC
Business Acquisition [Line Items]
Equity interest in acquiree, percentage										62.50%
RiverBanc
Business Acquisition [Line Items]
Goodwill purchase accounting adjustments		$ 20,000
Intangible assets				3,500,000
Goodwill				$ 25,222,000
Measurement period adjustment in intangible assets					$ 400,000
Goodwill impairment	$ 0
RiverBanc \| Minimum
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life				1 year
RiverBanc \| Maximum
Business Acquisition [Line Items]
Finite-lived intangible asset, useful life				10 years
RBMI, RBDHC
Business Acquisition [Line Items]
Gain on bargain purchase on businesses acquired				$ 65,000				$ 100,000