Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2024

Fair Value Disclosures [Abstract]

Schedule of changes in Investments

The change in our investments for the three-month and nine-month periods ended September 30, 2024 and 2023 are as follows:

	Three Months Ended September 30, 2024
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs		Significant Unobservable Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
	(in thousands)
Investment balance at beginning of period	$	13,279	$	—	$	7,148	$	20,427
Purchase of investments	—		1,000		21		1,021
Reclassification between Level 2 and Level 3 fair value	—		350		(350)		—
Unrealized gain on equity securities	1,072		38		193		1,303
Unrealized loss on embedded option	—		—		(553)		(553)
Unrealized gain on convertible note, excluding embedded option	—		—		556		556
Investment balance at end of period	$	14,351	$	1,388	$	7,015	$	22,754

	Three Months Ended September 30, 2023
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Unobservable Inputs
	(Level 1)		(Level 3)		Total
	(in thousands)
Investment balance at beginning of period	$	10,199	$	6,519	$	16,718
Purchase of investments	—		100		100
Unrealized loss on equity securities	(707)		—		(707)
Unrealized gain on embedded option	—		148		148
Unrealized gain on convertible note, excluding embedded option	—		146		146
Investment balance at end of period	$	9,492	$	6,913	$	16,405

	Nine Months Ended September 30, 2024
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs		Significant Unobservable Inputs
	(Level 1)		(Level 2)		(Level 3)		Total
	(in thousands)
Investment balance at beginning of period	$	10,154	$	—	$	7,200	$	17,354
Purchase of investments	—		1,000		21		1,021
Reclassification between Level 2 and Level 3 fair value	—		350		(350)		—
Unrealized gain on equity securities	4,197		38		1,070		5,305
Unrealized loss on embedded option	—		—		(1,714)		(1,714)
Unrealized gain on convertible note, excluding embedded option	—		—		788		788
Investment balance at end of period	$	14,351	$	1,388	$	7,015	$	22,754

	Nine Months Ended September 30, 2023
	Fair Value Measurements Using
	Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Unobservable Inputs
	(Level 1)		(Level 3)		Total
	(in thousands)
Investment balance at beginning of period	$	8,147	$	6,139	$	14,286
Purchase of investments	—		350		350
Unrealized gain on equity securities	1,345		—		1,345
Unrealized loss on embedded option	—		(50)		(50)
Unrealized gain on convertible note, excluding embedded option	—		474		474
Investment balance at end of period	$	9,492	$	6,913	$	16,405

Schedule of Recurring Fair Value Measurements

Recurring fair value measurements by valuation hierarchy as of September 30, 2024 and December 31, 2023 are as follows:

			Fair Value Measurements Using
	Total as of		Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	September 30, 2024		(Level 1)		(Level 2)		(Level 3)
	(in thousands)
Investment in Kodiak	$	13,063	$	13,063	$	—	$	—
Investment in CarbonFree	6,805		—		—		6,805
Investment in Standard Lithium	1,288		1,288		—		—
Investment in KMX Technologies	1,598		—		1,388		210
Total investments	$	22,754

			Fair Value Measurements Using
	Total as of		Quoted Prices in Active Markets for Identical Assets or Liabilities		Significant Other Observable Inputs		Significant Unobservable Inputs
Description	December 31, 2023		(Level 1)		(Level 2)		(Level 3)
	(in thousands)
Investment in CSI Compressco	$	8,538	$	8,538	$	—	$	—
Investment in CarbonFree	6,850		—		—		6,850
Investment in Standard Lithium	1,616		1,616		—		—
Investment in KMX Technologies	350		—		—		350
Investments	$	17,354