Annual report pursuant to Section 13 and 15(d)

Stockholders' Equity and Mezzanine Equity - Dividends Declared (Detail)

v3.6.0.2
Stockholders' Equity and Mezzanine Equity - Dividends Declared (Detail) - $ / shares
 12 Months Ended
Dec. 31, 2016
Dec. 31, 2015
Dec. 31, 2014
Senior Common Stock [Member]      
Dividends Payable [Line Items]      
Common stock, cash paid (in dollars per share) $ 1.0500 $ 1.0500 $ 1.0500
Series A Preferred Stock [Member]      
Dividends Payable [Line Items]      
Preferred stock, cash paid (in dollars per share) 1.9374996 1.9374996 1.9374996
Series B Preferred Stock [Member]      
Dividends Payable [Line Items]      
Preferred stock, cash paid (in dollars per share) 1.8750 1.8750 1.8750
Series C Preferred Stock [Member]      
Dividends Payable [Line Items]      
Preferred stock, cash paid (in dollars per share) 1.1330 1.7813 1.7813
Series D Preferred Stock [Member]      
Dividends Payable [Line Items]      
Preferred stock, cash paid (in dollars per share) 1.0538 0.0000 0.0000
Common Stock [Member]      
Dividends Payable [Line Items]      
Common stock, cash paid (in dollars per share) $ 1.500 $ 1.500 $ 1.500