Debt - Summary of Borrowings (Parenthetical) (Detail)	3 Months Ended
Mar. 31, 2020 USD ($) Swap
CBP Savannah [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	4.12%
ICE Charleston [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	3.93%
MEPCOM Jacksonville [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	3.89%
USFS II Albuquerque [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	3.92%
DEA Pleasanton [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	1.80%
VA Loma Linda [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	3.78%
VA Golden [Member] \| Mortgage Notes Payable [Member]
Debt Instrument [Line Items]
Effective interest rate	5.03%
2018 Term Loan Facility [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity	$ 150,000,000.0
2018 Term Loan Facility [Member] \| Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Number of forward interest rate swaps \| Swap	4
Forward swaps effective date	Dec. 13, 2018
Aggregate notional value of interest rate swaps	$ 150,000,000.0
Forward swaps interest rate	3.96%
2016 Term Loan Facility [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Accordion Feature Additional Borrowing Capacity	$ 100,000,000.0
2016 Term Loan Facility [Member] \| Interest Rate Swaps [Member]
Debt Instrument [Line Items]
Number of forward interest rate swaps \| Swap	2
Forward swaps effective date	Mar. 29, 2017
Aggregate notional value of interest rate swaps	$ 100,000,000.0
Forward swaps interest rate	2.67%
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Line Of Credit Facility Maximum Borrowing Capacity	$ 450,000,000.0
Line Of Credit Facility Accordion Feature Additional Borrowing Capacity	250,000,000.0
Amount available under revolving credit facility	$ 414,000,000.0
Line of Credit Facility, Description	revolving credit facility has two six-month as-of-right extension options subject to certain conditions and the payment of an extension fee
LIBOR [Member]
Debt Instrument [Line Items]
Loan, interest rate	0.99%

Line of credit facility accordion feature additional borrowing capacity.

No definition available.

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Namespace Prefix:	dea_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Effective interest rate for the funds borrowed under the debt agreement considering interest compounding and original issue discount or premium.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 6
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6036836-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Fixed interest rate related to the interest rate derivative.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeFixedInterestRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Date the entity entered into the derivative contract, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

Name:	us-gaap_DerivativeInceptionDates
Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
Balance Type:	na
Period Type:	duration

- Definition

Nominal or face amount used to calculate payment on derivative.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

+ Details

Name:	us-gaap_DerivativeNotionalAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	na
Period Type:	instant

- Definition

Description of the terms of a credit facility arrangement. Terms typically include interest rate, collateral required, guarantees required, repayment requirements, and restrictions on use of assets and activities of the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.19(b),22(b))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of interest rate derivative instruments held by the entity at the reporting date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1A
-Subparagraph (d)
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5579245-113959

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 815
-SubTopic 10
-Section 50
-Paragraph 1B
-URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5580258-113959

+ Details

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Balance Type:	na
Period Type:	instant

- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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- Details

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