Note 3 - Revenues from Contracts with Customers (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer, Excluding Assessed Tax	$ 307,013	$ 185,196	$ 120,166
Mineral Rights Segment [Member] | Transportation and Processing Services [Member]
Revenue from Contract with Customer, Excluding Assessed Tax	17,900	5,400	5,000
Sales-type Lease, Revenue	$ 3,200	$ 3,600	$ 3,800