Cover Page - shares	6 Months Ended
	Jun. 30, 2020	Aug. 05, 2020
Class of Stock [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Jun. 30, 2020
Document Transition Report	false
Entity File Number	000-55605
Entity Registrant Name	Griffin Capital Essential Asset REIT, Inc.
Entity Incorporation, State or Country Code	MD
Entity Tax Identification Number	46-4654479
Entity Address, Address Line One	1520 E. Grand Ave
Entity Address, City or Town	El Segundo
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	90245
City Area Code	310
Local Phone Number	469-6100
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Central Index Key	0001600626
Amendment Flag	false
Document Fiscal Year Focus	2020
Document Fiscal Period Focus	Q2
Current Fiscal Year End Date	--12-31
Common Class T
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		554,920
Common Class S
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		1,802
Common Class D
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		40,688
Common Class I
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		1,892,807
Common Class A
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		24,281,704
Common Class AA
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		47,180,973
Common Class AAA
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		916,682
Common Class E
Class of Stock [Line Items]
Entity Common Stock, Shares Outstanding		155,315,836