Note 9 - Fair Value Measurements - Fair Value of Financial Assets and Liabilities (Details) - USD ($) $ in Thousands		Sep. 30, 2022	Dec. 31, 2021
Long term debt, carry value		$ 238,723	$ 433,545
Contract receivable, net (current and long-term) (2)	[1]	31,948	33,612
Fair Value, Inputs, Level 3 [Member]
Contract receivable, net (current and long-term) (2)	[1]	25,144	26,010
Nine Point One Two Five Percent Senior Notes Due June Two Zero Two Five [Member]
Long term debt, carry value		120,199	296,236
Long term debt, fair value		124,165	300,000
Opco Senior Notes [Member]
Long term debt, carry value	[2]	118,524	137,309
Long term debt, fair value	[2]	122,146	138,484
Floating Rate Revolving Credit Facility Due April 2023 [Member]
Long term debt, carry value		0	0
Long term debt, fair value		$ 0	$ 0

[1] The fair value of the Partnership's contract receivable is determined based on the present value of future cash flow projections related to the underlying asset at a discount rate of 15% at September 30, 2022 and December 31, 2021.

[2] The fair value of the Opco Senior Notes are estimated by management using quotations obtained for the NRP 2025 Senior Notes on the closing trading prices near period end, which were at 102% and 100% of par value at September 30, 2022 and December 31, 2021, respectively. All 2025 Senior Notes were redeemed in October 2022.