Annual report pursuant to Section 13 and 15(d)

Organization, Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)

v3.3.1.900
Organization, Basis of Presentation and Significant Accounting Policies - Additional Information (Detail)
 12 Months Ended
Dec. 31, 2015
USD ($)
Subsidiary
shares
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Organization And Significant Accounting Policies [Line Items]      
Number of subsidiaries interest owned in general and limited partnership | Subsidiary 2    
Non-qualifying income related to real estate portfolio $ 0    
Amortization related to below-market lease 900,000 $ 700,000 $ 600,000
Total amortization expense related to intangible assets $ 13,100,000 10,000,000 7,300,000
Maturity period of highly-liquid investments at the time of purchase Three months or less    
Payments of deferred financing costs $ 1,880,000 1,029,000 2,051,000
Total amortization expense related to deferred financing costs is included in interest expense $ 1,955,000 1,656,000 1,780,000
Deferred rent expense   800,000  
Uncertain tax positions percentage 50.00%    
Uncertain tax positions $ 0 0 0
Liabilities accrued 100,000 400,000 0
Expenses recorded to general and administrative expense 200,000 100,000 100,000
Aggregate undiscounted obligation on properties 9,000,000    
Expected payment to be made in next twelve months 0    
Expected payment to be made in second year 0    
Expected payment to be made in third year 0    
Expected payment to be made in fourth year 0    
Expected payment to be made in fifth year $ 0    
Minimum [Member]      
Organization And Significant Accounting Policies [Line Items]      
Expected lease up period for estimating carrying costs 9 months    
Remaining term of in-place leases and unamortized lease 7 years    
REIT taxable income to its stockholders 90.00%    
Percentage of discount rate for calculating undiscounted obligation 2.50%    
Maximum [Member]      
Organization And Significant Accounting Policies [Line Items]      
Expected lease up period for estimating carrying costs 18 months    
Remaining term of in-place leases and unamortized lease 15 years    
REIT taxable income to its stockholders 100.00%    
Percentage of discount rate for calculating undiscounted obligation 7.60%    
Above Market Leases [Member]      
Organization And Significant Accounting Policies [Line Items]      
Amortization related to above-market lease $ 400,000 300,000 300,000
Buildings and Improvements [Member]      
Organization And Significant Accounting Policies [Line Items]      
Estimated useful life 39 years    
Equipment and Fixtures [Member] | Minimum [Member]      
Organization And Significant Accounting Policies [Line Items]      
Estimated useful life 5 years    
Equipment and Fixtures [Member] | Maximum [Member]      
Organization And Significant Accounting Policies [Line Items]      
Estimated useful life 20 years    
Building and Tenant Improvements [Member]      
Organization And Significant Accounting Policies [Line Items]      
Real estate depreciation expense $ 22,200,000 $ 18,800,000 $ 15,500,000
Gladstone Commercial Advisers, Inc. [Member]      
Organization And Significant Accounting Policies [Line Items]      
Company ownership percentage of voting securities of Commercial Advisers 100.00%    
GCLP Business Trust I [Member]      
Organization And Significant Accounting Policies [Line Items]      
Percentage of limited partnership interest transferred to business unit 99.00%    
Number of trust shares exchanged for limited partnership interest | shares 100    
Subsidiary and business trust of the Company, formed under the laws of the Commonwealth of Massachusetts, date Dec. 28, 2005    
GCLP Business Trust II [Member]      
Organization And Significant Accounting Policies [Line Items]      
Percentage of limited partnership interest transferred to business unit 1.00%    
Number of trust shares exchanged for general partnership interest | shares 100    
Subsidiary and business trust of the Company, formed under the laws of the Commonwealth of Massachusetts, date Dec. 28, 2005