Note 2 - Significant Accounting Policies - Activity in Bitcoin (Details)	3 Months Ended								9 Months Ended
	Sep. 30, 2025 USD ($)		Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)	Sep. 30, 2024 USD ($)		Jun. 30, 2024 USD ($)	Mar. 31, 2024 USD ($)	Sep. 30, 2025 USD ($)		Sep. 30, 2024 USD ($)
Beginning balance	696,875			551,918	306,979			0	551,918		0
Beginning balance, average cost	$ 53,376,118,281			$ 37,372,942,571	$ 17,749,065,590			$ 0	$ 37,372,942,571		$ 0
Beginning balance, fair value	$ 74,720,071,026			51,530,013,513	$ 19,453,015,133			0	$ 51,530,013,513		$ 0
Bitcoin purchased	86,526	[1]			60,053				277,414	[1]	367,805
Bitcoin purchased, average cost	$ 10,027,666,255	[1]			$ 3,796,560,491				$ 29,274,422,450	[1]	$ 21,589,313,309
Bitcoin purchased, fair value	$ 10,027,666,255	[1]			$ 3,796,560,491				$ 29,274,422,450	[1]	$ 21,589,313,309
Bitcoin sold for the redemption of shares	(12,944)				(391)				(58,162)		(1,031)
Bitcoin sold for the redemption of shares, average cost	$ (1,031,277,204)				$ (22,898,817)				$ (4,224,068,823)		$ (59,047,292)
Bitcoin sold for the redemption of shares, fair value	(1,475,656,961)				(22,812,387)				(5,547,231,539)		(59,833,750)
Bitcoin sold for the redemption of shares, realized gain (loss)	$ 444,379,757				$ (86,430)				$ 1,323,162,716		$ 786,458
Bitcoin sold to pay expenses	(446)				(193)				(1,159)		(326)
Bitcoin sold to pay expenses, average cost	$ (35,091,335)				$ (11,212,559)				$ (85,880,201)		$ (18,751,312)
Bitcoin sold to pay expenses, fair value	(50,019,045)				(10,650,112)				(116,935,988)		(19,643,995)
Bitcoin sold to pay expenses, realized gain (loss)	14,927,710				(562,447)				31,055,787		892,683
Net realized gain (loss), fair value	459,307,467	[2]	$ 262,071,190	632,839,846	(648,877)	[3]	$ 2,227,493	100,525	1,354,218,503	[4]	1,679,141	[5]
Net change in unrealized appreciation/depreciation, fair value	$ 4,271,556,131		$ 14,244,730,958	(7,057,849,155)	$ 119,089,128		$ (2,102,796,450)	3,806,745,993	$ 11,458,437,934		$ 1,823,038,671
Ending balance	770,011		696,875		366,448		306,979		770,011		366,448
Ending balance, average cost	$ 62,337,415,997		$ 53,376,118,281		$ 21,511,514,705		$ 17,749,065,590		$ 62,337,415,997		$ 21,511,514,705
Ending balance, fair value	87,952,924,873		74,720,071,026		23,334,553,376		19,453,015,133		87,952,924,873		23,334,553,376
Ending balance, realized gain (loss)	$ 459,307,467	[2]	$ 262,071,190	$ 632,839,846	$ (648,877)	[3]	$ 2,227,493	$ 100,525	$ 1,354,218,503	[4]	$ 1,679,141	[5]

[1] Includes Bitcoin purchased for Shares issued of $1,526,838,414.

[2] Includes $462,736,525 of realized gains and $(3,429,058) of realized losses.

[3] Includes $2,603,378 of realized gains and $(3,252,255) of realized losses.

[4] Includes $1,465,817,600 of realized gains and $(111,599,097) of realized losses.

[5] Includes $7,965,631 of realized gains and $(6,286,490) of realized losses.