Oil and Natural Gas Interests (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Oil and natural gas interests:
Subject to depletion	$ 319,487	$ 311,954
Not subject to depletion	32,463	37,580
Gross oil and natural gas interests	351,950	349,534
Accumulated depletion and impairment	(144,445)	(130,342)
Oil and natural gas interests, net	$ 207,505	$ 219,192

Amount of accumulated depreciation, depletion, amortization and impairment of oil and gas property carried under the successful effort method.

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Oil and Gas properties, gross, carried under the successful effort method.

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Oil and gas properties net of accumulated depreciation, depletion, amortization, impairment, and abandonment, carried under the successful effort method.

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Oil and Gas properties with proved reserves under the successful effort method.

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Oil and Gas properties with unproved reserves under the successful effort method.

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