Gladstone Commercial Corporation Quarterly report pursuant to Section 13 or 15(d)

Real Estate and Intangible Assets - Carrying Value of Intangible Assets and Accumulated Amortization (Detail) - USD ($) $ in Thousands	Mar. 31, 2019	Dec. 31, 2018
Finite-Lived Intangible Assets [Line Items]
Below market leases and deferred revenue, gross	$ (30,822)	$ (29,807)
Below market leases and deferred revenue, accumulated amortization	13,051	12,502
Lease Intangibles
Finite-Lived Intangible Assets [Line Items]
Lease Intangibles	205,025	204,020
Accumulated Amortization	(96,978)	(92,572)
In-place leases
Finite-Lived Intangible Assets [Line Items]
Lease Intangibles	84,326	83,894
Accumulated Amortization	(42,388)	(40,445)
Leasing costs
Finite-Lived Intangible Assets [Line Items]
Lease Intangibles	60,049	59,671
Accumulated Amortization	(29,436)	(28,092)
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Lease Intangibles	60,650	60,455
Accumulated Amortization	(25,154)	(24,035)
Above market leases and below market leases and deferred revenue
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets (liabilities), gross	(16,247)	(15,256)
Finite-lived intangible assets (liabilities), accumulated amortization	3,843	3,521
Above market leases
Finite-Lived Intangible Assets [Line Items]
Lease Intangibles	14,575	14,551
Accumulated Amortization	$ (9,208)	$ (8,981)