Gladstone Commercial Corporation Annual report pursuant to Section 13 and 15(d)

Annual report pursuant to Section 13 and 15(d)

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

Mortgage Notes Payable and Credit Facility - Additional Information (Detail)			1 Months Ended
	Jul. 02, 2019 USD ($)	Oct. 27, 2017 USD ($)	Oct. 31, 2015 USD ($)	Dec. 31, 2020 USD ($) property mortgage	Dec. 31, 2019 USD ($)	Jul. 01, 2019 USD ($)	Oct. 26, 2017 USD ($)
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property				118
Long-term debt				$ 668,692,000	$ 626,594,000
Line of credit facility, maximum borrowing capacity	$ 160,000,000.0	$ 75,000,000.0				$ 75,000,000.0	$ 25,000,000.0
Borrowings under revolving credit facility, net				$ 53,312,000	51,579,000
Line of credit at an interest rate (as percent)				1.76%
Weighted average interest rate on debt outstanding (as percent)				3.45%
Mortgage notes payable
Debt Instrument [Line Items]
Number of mortgage notes payable \| mortgage				53
Number of properties collateralized in mortgage notes payable \| property				68
Net book value of collateralized mortgage properties				$ 687,600,000
Fair value of mortgage notes payable outstanding				468,600,000
Long-term debt				$ 456,177,000	$ 453,739,000
Weighted average interest rate on debt outstanding (as percent)				4.24%
LIBOR
Debt Instrument [Line Items]
Spread on LIBOR (as percent)		2.75%
Term loan facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	160,000,000.0
Revolving credit facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity	$ 100,000,000.0					$ 85,000,000.0
Line of credit
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 85,000,000.0
Reduction at each of the leverage tiers (as percent)	0.10%	0.25%
Borrowings under revolving credit facility, net				$ 213,900,000
Letters of credit, outstanding				16,400,000
Line of credit facility, maximum additional amount drawn				$ 19,200,000
Line of credit \| Five year term loan facility
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity			$ 25,000,000.0
Debt instrument term			5 years
Line of credit \| Term loan facility
Debt Instrument [Line Items]
Debt instrument term	5 years
Line of credit \| Revolving credit facility
Debt Instrument [Line Items]
Debt instrument term	4 years
Debt instrument, fee	$ 1,300,000
Letter of credit
Debt Instrument [Line Items]
Weighted average interest rate on debt outstanding (as percent)				1.65%
Minimum \| Term loan facility \| LIBOR
Debt Instrument [Line Items]
Spread on LIBOR (as percent)	2.50%
Maximum \| Term loan facility \| LIBOR
Debt Instrument [Line Items]
Spread on LIBOR (as percent)	2.75%