Fair Value of ZEN - Summary of changes in quantity of ZEN and respective fair value (Detail) $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Jun. 30, 2025 USD ($) Horizen	Jun. 30, 2024 USD ($)	Jun. 30, 2025 USD ($) Horizen	Jun. 30, 2024 USD ($) Horizen	Sep. 30, 2024 USD ($) Horizen
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment, Type [Extensible Enumeration]	Investment in ZEN [Member]		Investment in ZEN [Member]		Investment in ZEN [Member]
Investment Owned, Balance, Contracts | Horizen			586,285.79535365	601,138.55454194	601,138.55454194
ZEN contributed | Horizen			390,780.33096177		0
ZEN distributed for Sponsor's Fee, related party | Horizen			(15,615.97219101)		(14,852.75918829)
Net change in unrealized appreciation (depreciation) on investment in ZEN | Horizen			0		0
Net realized loss on investment in ZEN | Horizen			0		0
Investment Owned, Balance, Contracts | Horizen	961,450.15412441		961,450.15412441		586,285.79535365
Investment Owned, at Fair Value | $			$ 4,767	$ 4,671	$ 4,671
ZEN contributed | $			6,599		0
ZEN distributed for Sponsor's Fee, related party | $			(198)		(140)
Net change in unrealized appreciation (depreciation) on investment in ZEN | $	$ (1,305)	$ (4,805)	(3,966)	(519)	400
Net realized loss on investment in ZEN | $	(61)	$ (43)	(106)	$ (121)	(164)
Investment Owned, at Fair Value | $	$ 7,096		$ 7,096		$ 4,767