Organization and Investment Objective (Details)	6 Months Ended
Jun. 30, 2018
Organization and Investment Objective [Line Items]
Required Distribution of Taxable Net Income, Percentage on Annual Basis	90.00%
Intended Distribution of Taxable Net Income, Percentage on Annual Basis	100.00%

Percentage of taxable income the Company is required to distribute on an annual basis.

No definition available.

Name:	earn_RequiredDistributionofTaxableNetIncomePercentageonAnnualBasis
Namespace Prefix:	earn_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration