Fair Value Measurements (Tables)

6 Months Ended

Jun. 30, 2024

Derivative Instruments and Hedging Activities Disclosure [Abstract]

Schedule of changes in Investments

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

	Three Months Ended June 30, 2024
	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	$	13,148	$	7,238	$	20,386
Unrealized gain on equity securities	131		—		131
Unrealized loss on embedded option	—		(85)		(85)
Unrealized loss on convertible note, excluding embedded option	—		(5)		(5)
Investment balance at end of period	$	13,279	$	7,148	$	20,427
	Three Months Ended June 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	$	7,963	$	5,939	$	13,902
Purchase of investments	—		250		250
Unrealized gain on equity securities	2,236		—		2,236
Unrealized gain on embedded option	—		123		123
Unrealized gain on convertible note, excluding embedded option	—		207		207
Investment balance at end of period	$	10,199	$	6,519	$	16,718

	Six Months Ended June 30, 2024
	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	$	10,154	$	7,200	$	17,354
Unrealized gain on equity securities	3,125		—		3,125
Unrealized loss on embedded option	—		(284)		(284)
Unrealized gain on convertible note, excluding embedded option	—		232		232
Investment balance at end of period	$	13,279	$	7,148	$	20,427
	Six Months Ended June 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	—		250		250
Unrealized gain on equity securities	2,052		—		2,052
Unrealized loss on embedded option	—		(198)		(198)
Unrealized gain on convertible note, excluding embedded option	—		328		328
Investment balance at end of period	$	10,199	$	6,519	$	16,718

Schedule of Recurring Fair Value Measurements

Recurring fair value measurements by valuation hierarchy as of June 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	June 30, 2024		(Level 1)		(Level 2)		(Level 3)
	(in thousands)
Investment in Kodiak	$	12,279	$	12,279	$	—	$	—
Investment in CarbonFree	6,798		—		—		6,798
Investment in Standard Lithium	1,000		1,000		—		—
Other investments	350		—		—		350
Total investments	$	20,427

			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		—		—
Other investments	350		—		—		350
Investments	$	17,354