Note 11 - Commitments and Contingencies (Details Textual)	12 Months Ended
Dec. 31, 2019
Minimum [Member]
Commitments to Extend Credit Estimated Completion or Termination Period	90 days
Maximum [Member]
Commitments to Extend Credit Estimated Completion or Termination Period	1 year

Termination period on commitments to extend credit.

No definition available.

Name:	ebmt_CommitmentsToExtendCreditEstimatedCompletionOrTerminationPeriod
Namespace Prefix:	ebmt_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration