Quarterly report pursuant to Section 13 or 15(d)

Equity and Mezzanine Equity - Additional Information (Detail)

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Equity and Mezzanine Equity - Additional Information (Detail) - USD ($)
$ in Millions
 6 Months Ended 9 Months Ended
Jun. 30, 2022
Sep. 30, 2021
Dec. 31, 2021
Feb. 20, 2020
Feb. 19, 2020
Jan. 29, 2020
Class of Stock [Line Items]            
Temporary equity, contract terms, trigger change in control 50.00%          
Common stock, shares outstanding (in shares) 39,136,473   37,473,587 60,290,000 86,290,000  
Units held by noncontrolling owners (in shares) 256,994 256,994        
Gladstone Commercial Limited Partnership            
Class of Stock [Line Items]            
Company ownership percentage of voting securities 99.30%   99.30%      
Number of units redeemed in acquisition (in shares) 246,039          
Series D Preferred Stock            
Class of Stock [Line Items]            
Temporary equity, contract terms, minimum vote needed to trigger change in control from tender offer 90.00%          
Preferred stock | Series E Preferred Stock            
Class of Stock [Line Items]            
Redeemable preferred stock, dividend rate 6.625%          
Preferred stock | Series G Preferred Stock            
Class of Stock [Line Items]            
Redeemable preferred stock, dividend rate 6.00%          
Preferred stock | Series F Preferred Stock            
Class of Stock [Line Items]            
Redeemable preferred stock, shares issued (in shares) 126,028          
Consideration received $ 2.9          
Maximum remaining capacity to sell common stock under open market sale agreement $ 622.6          
Redeemable preferred stock, shares authorized (in shares)       26,000,000    
Common Stock ATM Program | Common Stock            
Class of Stock [Line Items]            
Universal registration statement, amount authorized           $ 63.0
Common Stock ATM Program | Baird, Goldman Sachs, Stifel, Fifth Third, and U.S. Bancorp Investments, Inc. | Common Stock            
Class of Stock [Line Items]            
Redeemable preferred stock, shares issued (in shares) 1,500,000          
Common Stock ATM Program | Baird, Goldman Sachs, Stifel, and Fifth Third | Common Stock            
Class of Stock [Line Items]            
Consideration received $ 31.7          
Maximum remaining capacity to sell common stock under open market sale agreement 35.5          
2020 Universal Shelf            
Class of Stock [Line Items]            
Universal registration statement, amount authorized $ 658.7         800.0
2020 Universal Shelf | Preferred stock | Series F Preferred Stock            
Class of Stock [Line Items]            
Universal registration statement, amount authorized           $ 636.5