Quarterly report pursuant to Section 13 or 15(d)

Equity and Mezzanine Equity - Additional Information (Detail)

v3.19.2
Equity and Mezzanine Equity - Additional Information (Detail) - USD ($)
 6 Months Ended
Apr. 11, 2018
Jun. 30, 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)   1,600,000    
Consideration received   $ 33,300,000    
Maximum remaining capacity to sell common stock under open market sale agreement   36,200,000    
2019 Universal Shelf        
Class of Stock [Line Items]        
Universal registration statement, amount authorized   $ 469,800,000 $ 500,000,000