XML 75 R65.htm IDEA: XBRL DOCUMENT v3.5.0.2
Stockholders' Equity (Detail) - USD ($)
$ / shares in Units, $ in Thousands
 3 Months Ended 6 Months Ended
Jun. 17, 2016
Mar. 15, 2016
Jun. 30, 2016
Jun. 30, 2015
Mar. 31, 2015
Jun. 30, 2016
Jun. 30, 2015
Class of Stock [Line Items]              
Proceeds from issuance of common stock as a result of follow-on public offering         $ 193,148    
Dividend declared per share of common stock (in dollars per share)     $ 0.46 $ 0.44   $ 0.92 $ 0.88
Common Stock [Member]              
Class of Stock [Line Items]              
Dividend declared per share of common stock (in dollars per share) $ 0.46 $ 0.46          
Series A Preferred Stock [Member]              
Class of Stock [Line Items]              
Dividend rate, preferred stock           8.625%  
Dividend declared per share of preferred stock (in dollars per share) 0.5391 0.5391          
Series B Preferred Stock [Member]              
Class of Stock [Line Items]              
Dividend rate, preferred stock           8.00%  
Dividend declared per share of preferred stock (in dollars per share) $ 0.5000 $ 0.50          
Follow On Public Offering [Member] | Common Stock [Member]              
Class of Stock [Line Items]              
New issuance of stock (shares)         11,500,000    
Price per share of newly issued stock (in dollars per share)         $ 16.82