XML 81 R27.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Asset Impairments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2011
Asset Impairments [Abstract] |
Net book value and fair values of the assets |
|  | Fair Value |  |  | Net Book Value |
|  | (In thousands) |
Coal and other mineral rights, net |  | $ | 6,618 |  |  | $ | 76,003 |
Intangible assets, net |  |  | — |  |  |  | 43,855 |
Plant and equipment, net |  |  | 2,600 |  |  |  | 7,775 |
Total |  | $ | 9,218 |  |  | $ | 127,633 |
|  | Fair Value |  |  | Net Book Value |
|  | (In thousands) |
Coal and other mineral rights, net |  | $ | 20,035 |  |  | $ | 56,769 |
Intangible assets, net |  |  | — |  |  |  | 33,670 |
Plant and equipment, net |  |  | 2,947 |  |  |  | 2,947 |
Total |  | $ | 22,982 |  |  | $ | 93,386 |

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

X
- Definition Schedule of carrying value and fair value of assets. + References No definition available. + Details
Name: | nrp_ScheduleOfCarryingValueAndFairValueOfAssetsTableTextBlock
Namespace Prefix: | nrp_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration