Revenue - Summary of Revenue from Tenant Construction Projects Disaggregated by Tenant Agency (Detail) - ASU 2014-09 [Member] - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	$ 2,094	$ 496	$ 2,451	$ 1,761
Department of Veteran Affairs ("VA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	997	79	1,108	740
Environmental Protection Agency ("EPA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	115	90	204	90
Department of Transportation ("DOT") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		5	40	5
General Services Administration - Other [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income			25
Food And Drug Administration ("FDA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	6	51	24	51
Military Entrance Processing Command ("MEPCOM") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		45	18	66
U.S. Citizenship and Immigration Services ("USCIS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	91		108
Department of Energy (“DOE”) [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	95		95
Federal Emergency Management Agency ("FEMA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income			15
Federal Bureau of Investigation ("FBI") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	645	77	650	611
Internal Revenue Service ("IRS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	116	45	127	48
Bureau of the Fiscal Service ("BFS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		21	4	27
Health Resources and Services Administration ("HRSA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income			3
U.S Joint Staff Command ("JSC") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	25	41	26	41
The Judiciary of the U.S. Government ("JUD") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	$ 4		$ 4	1
U.S. Immigration and Customs Enforcement ("ICE") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		$ 42		62
Social Security Administration ("SSA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income				$ 19