Offsetting of Assets and Liabilities (Details) (USD $)
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Dec. 31, 2014
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Dec. 31, 2013
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Offsetting Assets and Liabilities [Line Items] |
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Securities Collateral Relating To Repurchase Agreements |
$ 1,390,000,000earn_SecuritiesCollateralRelatingToRepurchaseAgreements |
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$ 1,360,000,000earn_SecuritiesCollateralRelatingToRepurchaseAgreements |
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Financial derivatives–assets, at fair value |
3,072,000us-gaap_DerivativeAssets |
[1] |
34,963,000us-gaap_DerivativeAssets |
[1] |
Derivative Liability, Fair Value, Amount Offset Against Collateral |
(2,722,000)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral |
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(1,042,000)us-gaap_DerivativeFairValueOfDerivativeLiabilityAmountOffsetAgainstCollateral |
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Reverse repurchase agreements |
13,987,000us-gaap_SecuritiesPurchasedUnderAgreementsToResell |
[1] |
0us-gaap_SecuritiesPurchasedUnderAgreementsToResell |
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Securities sold under agreements to repurchase available for offset |
(13,987,000)earn_Securitiessoldunderagreementstorepurchaseavailableforoffset |
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Financial derivatives-liabilities, at fair value |
(8,700,000)us-gaap_DerivativeLiabilities |
[1] |
(1,069,000)us-gaap_DerivativeLiabilities |
[1] |
Derivative Asset, Fair Value, Amount Offset Against Collateral |
2,722,000us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral |
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1,042,000us-gaap_DerivativeFairValueOfDerivativeAssetAmountOffsetAgainstCollateral |
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Repurchase agreements |
(1,323,080,000)us-gaap_SecuritiesSoldUnderAgreementsToRepurchase |
[1] |
(1,310,347,000)us-gaap_SecuritiesSoldUnderAgreementsToRepurchase |
[1] |
Securities purchased under agreements to resell available for offset |
13,987,000earn_Securitiespurchasedunderagreementstoresellavailableforoffset |
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0earn_Securitiespurchasedunderagreementstoresellavailableforoffset |
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Derivative Financial Instruments, Assets [Member] |
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Offsetting Assets and Liabilities [Line Items] |
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Derivatives and related collateral, net |
350,000earn_Derivativesandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
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11,561,000earn_Derivativesandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
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Financial Instruments Pledged as Collateral |
0us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
[2],[3] |
0us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
[2],[4] |
Cash Collateral (Received) Pledged |
0us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
[2],[3] |
(22,360,000)us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
[2],[4] |
Excess cash collateral |
500,000earn_Excesscashcollateral / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
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300,000earn_Excesscashcollateral / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsAssetsMember |
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Reverse Repurchase Agreements [Member] |
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Offsetting Assets and Liabilities [Line Items] |
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Financial Instruments Pledged as Collateral |
0us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = earn_SecuritiesPurchasedunderAgreementstoResellMemberMember |
[2],[3] |
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Cash Collateral (Received) Pledged |
0us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = earn_SecuritiesPurchasedunderAgreementstoResellMemberMember |
[2],[3] |
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Reverse Repurchase Agreements and Related Collateral Net |
0earn_ReverseRepurchaseAgreementsandRelatedCollateralNet / us-gaap_FairValueByAssetClassAxis = earn_SecuritiesPurchasedunderAgreementstoResellMemberMember |
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Derivative Financial Instruments, Liabilities [Member] |
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Offsetting Assets and Liabilities [Line Items] |
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Derivatives and related collateral, net |
(195,000)earn_Derivativesandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
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(1,000)earn_Derivativesandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
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Financial Instruments Pledged as Collateral |
0us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
[2],[3] |
0us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
[2],[4] |
Cash Collateral (Received) Pledged |
5,783,000us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
[2],[3] |
26,000us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
[2],[4] |
Excess cash collateral |
6,300,000earn_Excesscashcollateral / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
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3,100,000earn_Excesscashcollateral / us-gaap_FairValueByAssetClassAxis = us-gaap_DerivativeFinancialInstrumentsLiabilitiesMember |
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Repurchase Agreements [Member] |
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Offsetting Assets and Liabilities [Line Items] |
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Repurchse agreements and related collateral, net |
0earn_Repurchseagreementsandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
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0earn_Repurchseagreementsandrelatedcollateralnet / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
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Financial Instruments Pledged as Collateral |
1,303,360,000us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
[2],[3] |
1,295,567,000us-gaap_FinancialInstrumentsOwnedAndPledgedAsCollateralAtFairValue / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
[2],[4] |
Cash Collateral (Received) Pledged |
$ 5,733,000us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
[2],[3] |
$ 14,780,000us-gaap_RestrictedCashAndCashEquivalents / us-gaap_FairValueByAssetClassAxis = us-gaap_SecuritiesSoldUnderAgreementsToRepurchaseMember |
[2],[4] |
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