XML 53 R10.htm IDEA: XBRL DOCUMENT
v3.22.1

Note 4 - Other Long-term Assets | 12 Months Ended
--- | ---
Dec. 31, 2021
Notes to Financial Statements |
Other Assets Disclosure [Text Block] | (4) OTHER LONG-TERM ASSETS (IN THOUSANDS)
|  | December 31, |
|  | 2021 |  |  | 2020 |
Advanced coal royalties |  | $ | 6,678 |  |  | $ | 6,449 |
Other |  |  | 1,694 |  |  |  | 1,809 |
Total other assets |  | $ | 8,372 |  |  | $ | 8,258 |

X
- References No definition available. + Details
Name: | us-gaap_DisclosureTextBlockAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for other assets. This disclosure includes other current assets and other noncurrent assets. + References No definition available. + Details
Name: | us-gaap_OtherAssetsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:textBlockItemType
Balance Type: | na
Period Type: | duration