Earnings Per Share - Summary of Basic and Diluted Earnings Per Common Share (Detail) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
		Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Earnings Per Share Basic And Diluted [Line Items]
Net income (loss)		$ 13,528	$ 8,224	$ 6,659
Less: Non-controlling interest in Operating Partnership		(1,567)	(1,017)	(955)
Net income available to Easterly Government Properties, Inc.		11,961	7,207	5,704
Less: Dividends on participating securities		(289)	(119)	(1,123)
Net income (loss) available to common stockholders		$ 11,672	$ 7,088	$ 4,581
Denominator for basic EPS		78,219,491	68,769,526	53,511,137
Denominator for diluted EPS		78,791,453	69,208,966	54,931,380
Basic EPS		$ 0.15	$ 0.10	$ 0.09
Diluted EPS		$ 0.15	$ 0.10	$ 0.08
Stock Compensation Plan [Member]
Earnings Per Share Basic And Diluted [Line Items]
Dilutive effect		55,567	22,855	9,510
Restricted Common Stock [Member]
Earnings Per Share Basic And Diluted [Line Items]
Dilutive effect	[1]	507,050	416,585	1,135,544
Forward Sales Agreements [Member]
Earnings Per Share Basic And Diluted [Line Items]
Dilutive effect	[2]	9,345		275,189

[1] During the years ended December 31, 2020 and December 31, 2018, there were approximately 74,481 and 173,381 unvested performance-based LTIP units, respectively, that were not included in the computation of diluted earnings per share because to do so would have been antidilutive for the period.

[2] During the years ended December 31, 2020 and 2019, there were approximately 2,397,232 and 2,878,703 shares, respectively, of underlying unsettled forward sales transactions that were not included in the computation of diluted earnings per share because to do so would have been antidilutive for the period