Note 2 - Significant Accounting Policies - Activity in Ether (Details)		1 Months Ended	3 Months Ended							4 Months Ended		9 Months Ended
	Jun. 24, 2024	Jun. 30, 2024 USD ($)	Sep. 30, 2025 USD ($)		Jun. 30, 2025 USD ($)	Mar. 31, 2025 USD ($)		Sep. 30, 2024 USD ($)		Sep. 30, 2024 USD ($)		Sep. 30, 2025 USD ($)
Beginning balance		0	1,768,573			1,071,415		3,031		0		1,071,415
Beginning balance, average cost		$ 0	$ 5,242,898,137			$ 3,543,902,275		$ 10,000,000		$ 0		$ 3,543,902,275
Beginning balance, fair value		0	$ 4,396,336,194			3,571,669,777	[1]	$ 10,590,295		$ 0		$ 3,571,669,777	[1]
Ether purchased	3,031		2,516,582					384,840		387,871		3,471,085
Ether purchased, average cost			$ 9,716,662,530					$ 1,147,427,156		$ 1,157,427,156		$ 12,249,273,102
Ether purchased, fair value			$ 9,716,662,530					$ 1,147,427,156		$ 1,157,427,156		$ 12,249,273,102
Ether sold for the redemption of shares			(441,125)									(697,568)
Ether sold for the redemption of shares, average cost			$ (1,471,657,646)									$ (2,302,367,865)
Ether sold for the redemption of shares, fair value			(1,798,740,023)									(2,332,927,732)
Ether sold for the redemption of shares, realized gain (loss)			$ 327,082,377									$ 30,559,867
Ether sold to pay expenses			(1,207)					(28)		(28)		(2,109)
Ether sold to pay expenses, average cost			$ (3,951,091)					$ (84,988)		$ (84,988)		$ (6,855,582)
Ether sold to pay expenses, fair value			(4,681,463)					(63,328)		(63,328)		(6,849,547)
Ether sold to pay expenses, realized gain (loss)			730,372					(21,660)		(21,660)		(6,035)
Net realized gain (loss), fair value			327,812,749	[2]	$ (93,604,071)	(203,654,846)		(21,660)	[3]	(21,660)	[3]	30,553,832	[4]
Net change in unrealized appreciation/depreciation, fair value		$ 590,295	$ 3,236,696,155		$ 854,250,640	(1,728,580,085)		$ (138,509,122)		$ (137,918,827)		$ 2,362,366,710
Ending balance		3,031	3,842,823		1,768,573			387,843		387,843		3,842,823
Ending balance, average cost		$ 10,000,000	$ 13,483,951,930		$ 5,242,898,137			$ 1,157,342,168		$ 1,157,342,168		$ 13,483,951,930
Ending balance, fair value		$ 10,590,295	15,874,086,142	[1]	4,396,336,194			1,019,423,341		1,019,423,341		15,874,086,142	[1]
Ending balance, realized gain (loss)			$ 327,812,749	[2]	$ (93,604,071)	$ (203,654,846)		$ (21,660)	[3]	$ (21,660)	[3]	$ 30,553,832	[4]

[1] Cost of investment in ether: $13,483,951,930 and $3,543,902,275, respectively.

[2] Includes $352,587,218 of realized gains and $(24,774,469) of realized losses.

[3] Includes $82 of realized gains and $(21,742) of realized losses.

[4] Includes $353,831,422 of realized gains and $(323,277,590) of realized losses.