Name:	nrc_DebtInstrumentCovenantExceptionFixedChargeCoverageRatioDividendThreshold
Namespace Prefix:	nrc_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The maximum cash flow leverage ratio the borrower is allowable to maintain under a debt instrument agreement.

No definition available.

Name:	nrc_DebtInstrumentCovenantMaximumCashFlowLeverageRatio
Namespace Prefix:	nrc_
Data Type:	xbrli:pureItemType
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Period Type:	duration

The minimum fixed charge coverage ratio the borrower is required to maintain under a debt instrument agreement.

No definition available.

Name:	nrc_DebtInstrumentCovenantMinimumFixedChargeCoverageRatio
Namespace Prefix:	nrc_
Data Type:	xbrli:pureItemType
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Period Type:	duration

The interest rate applicable to the portion of the carrying amount of debt instrument borrowings outstanding as of the balance sheet date, including current maturities, which accrues interest at a rate subject to change from time to time.

No definition available.

Name:	nrc_DebtInstrumentPercentageBearingVariableInterestPercentageRate
Namespace Prefix:	nrc_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

No definition available.

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
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Period Type:	duration

Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=119993939&loc=d3e28551-108399

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Name:	us-gaap_DebtInstrumentFaceAmount
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Contractual interest rate for funds borrowed, under the debt agreement.

Name:	us-gaap_DebtInstrumentInterestRateStatedPercentage
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Data Type:	num:percentItemType
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Amount of the required periodic payments including both interest and principal payments.

Name:	us-gaap_DebtInstrumentPeriodicPayment
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

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(22))
-URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=120398452&loc=d3e534808-122878

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=120400017&loc=d3e572229-122910

Name:	us-gaap_LineOfCredit
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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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.

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

The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility.

No definition available.

Name:	us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

Name:	us-gaap_DebtInstrumentAxis=nrc_CreditAgreementMember
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Name:	us-gaap_LineOfCreditFacilityAxis=nrc_FirstNationalBankOfOmahaMember
Namespace Prefix:
Data Type:	na
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Data Type:	na
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Name:	us-gaap_LongtermDebtTypeAxis=nrc_TermLoanMember
Namespace Prefix:
Data Type:	na
Balance Type:
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Name:	us-gaap_LongtermDebtTypeAxis=nrc_DelayedDrawTermLoanMember
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