Financial Highlights Per Share Performance - Summary of per share data (Detail) - $ / shares	12 Months Ended			39 Months Ended
	Jun. 30, 2025	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2025
Per Share Data:
Principal Market NAV, beginning of year	$ 6.37	$ 9.22	$ 4.61
Net increase (decrease) in net assets from investment operations:
Net investment loss		(0.17)	(0.16)	$ (0.19)
Net realized and unrealized gain (loss)		(2.68)	4.77	1.07
Net increase (decrease) in net assets resulting from operations		(2.85)	4.61	0.88
Principal Market NAV, end of year	$ 7.25	$ 6.37	$ 9.22	$ 7.25
Total return	13.81%	(30.91%)	100.00%
Ratios to average net assets:
Net investment loss	(2.50%)	(2.50%)	(2.50%)
Expenses	(2.50%)	(2.50%)	(2.50%)