Annual report pursuant to Section 13 and 15(d)

Mandatorily Redeemable Term Preferred Stock - Additional Information (Detail)

v3.6.0.2
Mandatorily Redeemable Term Preferred Stock - Additional Information (Detail) - USD ($)
$ / shares in Units, $ in Millions
 1 Months Ended 12 Months Ended
Feb. 29, 2012
Dec. 31, 2016
Dec. 31, 2015
Class of Stock [Line Items]      
Preferred Stock mandatory redemption date Jan. 31, 2017    
\Write -off of unamortized offering costs   $ 0.2  
Series C Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, dividend rate percentage (as percent) 7.125%    
Mandatorily Redeemable Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, shares issued (in shares) 1,540,000    
Redeemable preferred stock, par value (in dollars per share) $ 0.001    
Public offering price (in dollars per share) $ 25.00    
Gross proceeds of the offering $ 38.5    
Net proceeds, after deducting offering expenses $ 36.7    
Mandatorily Redeemable Preferred Stock [Member] | Series C Preferred Stock [Member]      
Class of Stock [Line Items]      
Redeemable preferred stock, shares issued (in shares)   0 1,540,000
Redeemable preferred stock, par value (in dollars per share)   $ 0.001 $ 0.001