Revenue - Summary of Revenue from Tenant Construction Projects Disaggregated by Tenant Agency (Detail) - ASU 2014-09 [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	$ 357	$ 1,265
Department of Veteran Affairs ("VA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	111	661
Environmental Protection Agency ("EPA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	89
Department of Transportation ("DOT") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	40
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	18
Military Entrance Processing Command ("MEPCOM") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	18	21
U.S. Citizenship and Immigration Services ("USCIS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	17
Federal Emergency Management Agency ("FEMA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	15
Internal Revenue Service ("IRS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	11	3
Federal Bureau of Investigation ("FBI") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	5	534
Bureau of the Fiscal Service ("BFS") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income	4	6
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	$ 1
U.S. Immigration and Customs Enforcement (“ICE”) [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		20
Social Security Administration ("SSA") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		19
The Judiciary of the U.S. Government ("JUD") [Member]
Disaggregation Of Revenue [Line Items]
Tenant Construction Project Income		$ 1