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

Quarterly report pursuant to Section 13 or 15(d)

Mortgage Notes Payable and Credit Facility - Additional Information (Detail)

Mortgage Notes Payable and Credit Facility - Additional Information (Detail)		3 Months Ended		9 Months Ended
	Jul. 02, 2019 USD ($)	Sep. 30, 2020 USD ($) property mortgage	Sep. 30, 2019 USD ($)	Sep. 30, 2020 USD ($) property mortgage	Sep. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)	Jul. 01, 2019 USD ($)
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property		120		120
Payments of deferred financing costs				$ 422,000	$ 2,075,000
Carrying value		$ 660,659,000		660,659,000		$ 626,594,000
Line of credit outstanding		$ 43,149,000		$ 43,149,000		51,579,000
Weighted average interest rate on debt outstanding (as percent)		4.28%		4.28%
Term loan facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 160,000,000.0						$ 75,000,000.0
Revolving credit facility
Debt Instrument [Line Items]
Maximum borrowing capacity	$ 100,000,000.0						$ 85,000,000.0
Line of credit
Debt Instrument [Line Items]
Extension fee on initial maturity (as percent)	0.10%
Line of credit outstanding		$ 203,800,000		$ 203,800,000
Weighted average interest rate (as percent)		1.76%		1.76%
Letters of credit, outstanding		$ 13,700,000		$ 13,700,000
Maximum additional amount that can be drawn under Line of Credit		$ 27,800,000		$ 27,800,000
Line of credit \| Term loan facility
Debt Instrument [Line Items]
Term of debt	5 years
Line of credit \| Revolving credit facility
Debt Instrument [Line Items]
Term of debt	4 years
Debt instrument fees incurred	$ 1,300,000
Letter of credit
Debt Instrument [Line Items]
Weighted average interest rate on debt outstanding (as percent)		1.65%		1.65%
Mortgage notes payable
Debt Instrument [Line Items]
Number of mortgage notes payable \| mortgage		54		54
Number of properties collateralized in mortgage notes payable \| property		69		69
Net book value of collateralized mortgage properties		$ 680,900,000		$ 680,900,000
Recourse amount of mortgage notes payable		800,000		$ 800,000
Percentage of debt recourse (as percent)				0.20%
Fair value of mortgage notes payable		473,400,000		$ 473,400,000
Carrying value		$ 458,364,000		$ 458,364,000		$ 453,739,000
Weighted average interest rate on debt outstanding (as percent)		3.51%		3.51%
Fixed rate mortgage loans
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property		61		61
Payments of deferred financing costs		$ 30,000.00	$ 1,400,000	$ 400,000	$ 2,100,000
Minimum \| LIBOR \| Term loan facility
Debt Instrument [Line Items]
Spread on LIBOR (as percent)	2.50%
Maximum \| LIBOR \| Term loan facility
Debt Instrument [Line Items]
Spread on LIBOR (as percent)	2.75%