Quarterly report pursuant to Section 13 or 15(d)

Equity and Mezzanine Equity - Additional Information (Detail)

v3.19.1
Equity and Mezzanine Equity - Additional Information (Detail) - USD ($)
 1 Months Ended 3 Months Ended
Apr. 11, 2018
Feb. 29, 2016
Mar. 31, 2019
Jan. 11, 2019
Dec. 31, 2018
Class of Stock [Line Items]          
Shares reclassified to common stock 3,500,000        
Senior common stock, authorized but unissued 57,969        
Capital stock, shares authorized 100,000,000        
Common stock, shares authorized 87,700,000   87,700,000   87,700,000
Series A and B Preferred Stock ATM Programs          
Class of Stock [Line Items]          
Redeemable preferred stock, shares issued (in shares)     2,264,000   2,264,000
Series D Cumulative Redeemable Preferred Stock          
Class of Stock [Line Items]          
Redeemable preferred stock, dividend rate percentage (as percent)     7.00%    
Temporary equity, contract terms, minimum vote needed to trigger change in control from tender offer (as percent)     90.00%    
Cantor Fitzgerald & Co | Preferred Stock | Series A and B Preferred Stock ATM Programs          
Class of Stock [Line Items]          
Redeemable preferred stock, shares issued (in shares)     0    
Maximum remaining capacity to sell preferred stock under open market sale agreement     $ 37,200,000    
Cantor Fitzgerald & Co | Preferred Stock | Series A Cumulative Redeemable Preferred Stock          
Class of Stock [Line Items]          
Redeemable preferred stock, dividend rate percentage (as percent)   7.75%      
Cantor Fitzgerald & Co | Preferred Stock | Series B Cumulative Redeemable Preferred Stock          
Class of Stock [Line Items]          
Redeemable preferred stock, dividend rate percentage (as percent)   7.50%      
Maximum aggregate sales price of shares to be issued under open market sale agreement   $ 40,000,000.0      
Cantor Fitzgerald & Co | Preferred Stock | Series D Cumulative Redeemable Preferred Stock          
Class of Stock [Line Items]          
Maximum aggregate sales price of shares to be issued under open market sale agreement     50,000,000.0    
Maximum remaining capacity to sell preferred stock under open market sale agreement     $ 18,600,000    
Common Stock ATM Program | Cantor Fitzgerald & Co | Common Stock          
Class of Stock [Line Items]          
Redeemable preferred stock, shares issued (in shares)     700,000    
Consideration received     $ 14,100,000    
Maximum remaining capacity to sell common stock under open market sale agreement     55,600,000    
2019 Universal Shelf          
Class of Stock [Line Items]          
Universal registration statement, amount authorized     $ 489,200,000 $ 500,000,000