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
	Jun. 22, 2017 USD ($)	Oct. 05, 2015 USD ($)	Sep. 30, 2017 USD ($) mortgage property	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($) mortgage lender property	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)	Aug. 31, 2013 USD ($)
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property			91		91
Number of long-term mortgages repaid \| mortgage					4
Number of properties repaid to collateralized mortgages notes payable \| mortgage					10
Payments of deferred financing costs					$ 992,000	$ 1,024,000
Fair value of mortgage notes payable			$ 461,800,000		$ 461,800,000
Maximum borrowing capacity		$ 150,000,000.0						$ 100,000,000.0
Expiration date		2019-08
Term of extended period		1 year
Optional extension period		1 year
Extension fee on initial maturity (as percent)		0.25%
Number of lenders added to agreement \| lender					3
Line of credit outstanding			$ 43,933,000		$ 43,933,000		$ 39,225,000
Weighted average interest rate on debt outstanding (as percent)			4.52%		4.52%
Term Loan Facility
Debt Instrument [Line Items]
Expiration date		2020-10
Extension fee on initial maturity (as percent)		0.05%
Line of credit
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 85,000,000.0
Line of credit outstanding			$ 69,200,000		$ 69,200,000
Weighted average interest rate (as percent)			3.22%		3.22%
Letters of credit, outstanding			$ 1,000,000		$ 1,000,000
Maximum additional amount that can be drawn under Line of Credit			$ 34,000,000		$ 34,000,000
Line of credit \| Term Loan Facility
Debt Instrument [Line Items]
Maximum borrowing capacity		$ 25,000,000.0
Letter of credit
Debt Instrument [Line Items]
Weighted average interest rate on debt outstanding (as percent)			2.00%		2.00%
Mortgage notes payable
Debt Instrument [Line Items]
Number of mortgage notes payable \| mortgage			45		45
Number of properties collateralized in mortgage notes payable \| property			67		67
Net book value of collateralized mortgage properties			$ 674,900,000		$ 674,900,000
Recourse amount of mortgage notes payable			11,700,000		$ 11,700,000
Percentage of debt recourse (as percent)					2.60%
Carrying value			$ 455,390,000		$ 455,390,000
Weighted average interest rate on debt outstanding (as percent)			4.34%		4.34%
Issued and assumed mortgage notes payable
Debt Instrument [Line Items]
Number of mortgage notes payable \| mortgage			4		4
Number of properties collateralized in mortgage notes payable \| property			7		7
Existing mortgage notes payable
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property			1		1
Fixed rate mortgage loans
Debt Instrument [Line Items]
Number of properties collateralized in mortgage notes payable \| property			48		48
Payments of deferred financing costs			$ 600,000	$ 400,000	$ 1,000,000	$ 1,000,000
Carrying value			$ 385,555,000		$ 385,555,000		$ 378,477,000
Weighted average interest rate on debt outstanding (as percent)			6.25%		6.25%
New fixed rate mortgage loans
Debt Instrument [Line Items]
Stated interest rate (as percent)			3.55%		3.55%
Debt assumed					$ 54,887,000
Weighted average interest rate on debt outstanding (as percent)			3.78%		3.78%
Conshohocken, Pennsylvania
Debt Instrument [Line Items]
Stated interest rate (as percent)	1.80%
Debt assumed	$ 11,200,000
Interest rate swap \| Conshohocken, Pennsylvania
Debt Instrument [Line Items]
Interest rate swap	40,000		$ 200,000		$ 200,000
Debt assumed	$ 11,200,000