Note 2 - Significant Accounting Policies (Details Textual)	Sep. 30, 2025 shares
Shares Prescribed Aggregation (in shares)	40,000

Prescribed aggregation at which shares are issued and redeemed.

No definition available.

Name:	etha_SharesPrescribedAggregation
Namespace Prefix:	etha_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant