Summary of Significant Accounting Policies Adoption of New Accounting Policies (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
Dec. 31, 2017	Dec. 31, 2017
Accounting Policies [Abstract]
Tax Cuts and Jobs Act of 2017, reclassification from AOCI to retained earnings	$ 863	$ 0

Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act of 2017.

No definition available.

Name:	emcf_TaxCutsandJobsActof2017ReclassificationfromAOCItoRetainedEarnings
Namespace Prefix:	emcf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration