Note 1 - Organization (Details Textual) - USD ($)		3 Months Ended						9 Months Ended
	Jan. 05, 2024	Sep. 30, 2025	Jun. 30, 2025	Mar. 31, 2025	Sep. 30, 2024	Jun. 30, 2024	Mar. 31, 2024	Sep. 30, 2025	Sep. 30, 2024
Shares of Stock Classifed as Temporary Equity Surrendered During Reporting Period (in shares)								102,360,000	2,444,000
Value of Stock Classified as Temporary Equity Surrendered During Reporting Period		$ 1,475,800,256	$ 1,171,825,263	$ 2,900,294,791	$ 35,985,368	$ 46,353,487	$ 100,000
Stock Issued During Period, Shares, New Issues (in shares)								488,360,000	646,440,000
Sponsors Fee Annualized Accrual Rate Based on Daily Net Asset Value	0.25%							0.25%
BlackRock Financial Management, Inc. [Member]
Shares of Stock Classifed as Temporary Equity Surrendered During Reporting Period (in shares)	4,000
Value of Stock Classified as Temporary Equity Surrendered During Reporting Period	$ 100,000
Shares Redeemed, Price Per Share (in dollars per share)	$ 25
Stock Issued During Period, Shares, New Issues (in shares)	400,000
Shares Issued, Price Per Share (in dollars per share)	$ 25
Stock Issued During Period, Value, New Issues	$ 10,000,000