XML 22 R48.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Long-Term Debt (Details Textuals) (USD $) In Millions, unless otherwise specified | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2011 | Aug. 10, 2011 | Dec. 31, 2010
Debt Instrument [Line Items] |  |  |
Ratio of consolidated indebtedness | no more than 4.0 to 1.0 |  |
Long-Term Debt (Textuals) [Abstract] |  |  |
Floating rate revolving credit facility |  | $ 300 |
Percentage of consolidated net tangible assets debt of subsidiaries not permitted to exceed | 10.00% |  |
Ratio of EBITDA to consolidated fixed charges | not less than 3.5 to 1.0 |  |
Partnerships leverage ratio | 3.75 to 1.00 |  |
Additional interest accrue | 2.00% |  |
Revolving Credit Facility Outstanding Balance | 0 |  | 94.0
Maximum increase in aggregate commitment |  | 500 |
Weighted average interest rate | 1.83% |  | 1.42%
Senior unsecured notes related with private placement | 300 |  |
Senior Notes [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Principal payments on its senior notes | $ 31.5 |  |
Credit Facility [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Ratio of consolidated indebtedness | 3.75 to 1.00 |  |
5.55% senior notes, with semi-annual interest payments in June and December, maturing June 2013 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.55% |  |
4.91% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2018 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 4.91% |  |
8.38% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2013, maturing in March 2019 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 8.38% |  |
5.05% senior notes, with semi-annual interest payments in January and July, with annual principal payments in July, maturing in July 2020 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.05% |  |
5.31% utility local improvement obligation, with annual principal and interest payments, maturing in March 2021 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of utility local improvement obligation | 5.31% |  |
5.55% senior notes, with semi-annual interest payments in June and December, with annual principal payments in June, maturing in June 2023 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.55% |  |
5.82% senior notes, with semi-annual interest payments in March and September, with annual principal payments in March, maturing in March 2024 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.82% |  |
8.92% senior notes, with semi-annual interest payments in March and September, with scheduled principal payments beginning March 2014, maturing in March 2024 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 8.92% |  |
$300 million floating rate revolving credit facility, due August 2016 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Commitment fee on the undrawn portion of the revolving credit facility rates | 0.18% to 0.40% |  |
4.73% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2023 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 4.73% |  |
5.03% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.03% |  |
5.18% senior notes, with semi-annual interest payments in June and December, with scheduled principal payments beginning December 2014, maturing in December 2026 [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Rate of Senior Notes due | 5.18% |  |
Maximum [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Revolving credit facility | 0.40% |  |
Minimum [Member] |  |  |
Debt Instrument [Line Items] |  |  |
Revolving credit facility | 0.18% |  |

X
- Definition Debt instrument additional variable interest rate. + References No definition available. + Details
Name: | nrp_DebtInstrumentAdditionalVariableInterestRate
Namespace Prefix: | nrp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | nrp_LongTermDebtTextualsAbstract
Namespace Prefix: | nrp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Partnerships leverage ratio. + References No definition available. + Details
Name: | nrp_PartnershipsLeverageRatio
Namespace Prefix: | nrp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of consolidated net tangible assets debt of subsidiaries not permitted to exceed. + References No definition available. + Details
Name: | nrp_PercentageOfConsolidatedNetTangibleAssetsDebtOfSubsidiariesNotPermittedToExceed
Namespace Prefix: | nrp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Rate of utility local improvement obligation. + References No definition available. + Details
Name: | nrp_RateOfUtilityLocalImprovementObligation
Namespace Prefix: | nrp_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ratio of EBITDA to consolidated fixed charges. + References No definition available. + Details
Name: | nrp_RatioOfEbitdaToConsolidatedFixedCharges
Namespace Prefix: | nrp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Ratio of indebtedness. + References No definition available. + Details
Name: | nrp_RatioOfIndebtedness
Namespace Prefix: | nrp_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Senior unsecured notes related with private placement. + References No definition available. + Details
Name: | nrp_SeniorUnsecuredNotesRelatedWithPrivatePlacement
Namespace Prefix: | nrp_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Decrease for amounts repaid on the debt instrument for the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 4 -Section 08 -Paragraph f Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(f)) -URI http://asc.fasb.org/extlink&oid=6881521&loc=d3e23780-122690 + Details
Name: | us-gaap_DebtInstrumentDecreaseRepayments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Interest rate stated in the contractual debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Description of the fees for amounts available, but unused under the credit facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCommitmentFeeDescription
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityCurrentBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- 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://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 129 -Paragraph 2, 4 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 Reference 3: http://www.xbrl.org/2003/role/presentationRef -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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19, 22 -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -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=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityRemainingBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The fee, expressed as a percentage of the line of credit facility, for available but unused credit capacity under the credit facility. + References No definition available. + Details
Name: | us-gaap_LineOfCreditFacilityUnusedCapacityCommitmentFeePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Reflects the calculation as of the balance sheet date of the average interest rate weighted by the amount of short-term debt outstanding by type or by instrument at that time. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 02 -Paragraph 19 -Subparagraph b -Article 5 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.19(b)) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_ShortTermDebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant